From jop at astro.columbia.edu Sat Mar 1 01:49:54 1997 From: jop at astro.columbia.edu (Joe Patterson) Date: Sat, 1 Mar 1997 01:49:54 -0500 Subject: (cba:news) stars of march Message-ID: <199703010649.BAA29252@tristram.phys.columbia.edu> Dear CBAers, March 1, 1997. OK, I have the S. African mail link set up now. You can reach me at jop at astro.columbia.edu. That's the preferred address for letters, whereas Columbia is still preferred for data. But either is fine. We've just finished a mini-campaign on BH Lyn and DW UMa. One of those full-moon specials, sorry about that. Weather at all stations ranged from average to very poor, so our haul was pretty thin. But we got enough to close the books happily on BH Lyn for the observing season. DW UMa continues to be of extraordinary interest, and I certainly hope you make friends with this excellent star. We will be working on it as the prime target for many (most) of us for the next six weeks. Now there's still EG Cancri. Still superhumping a couple of weeks ago at magnitude 17.4. Now probably a little fainter; the Ouda photometry placed it at 17.85. Keep close watch for further echoes. I think the "star of the week" folks have turned away from it, and the likelihood that humans will see another echo is not great (the echo only lasts ~1 day). So let's us do our part. Even if you can't get time series, snapshot photometry would be very useful (including upper limits). (Warren, this is a good target for your occasional potshots.) Which brings us to... er, the star of the week. Namely, T Leo, back in superoutburst after about 4 years. Until this Xmas, I would've said it was "just another SU UMa star", with Porb and Psh known, so why bother? The reason is: ECHO OUTBURSTS. EG Cnc may be the king of echo outbursts, but T Leo has flung a few at us in the past, and because it is the brightest of the known echoers, it could provide crucial information on just what are these strange surges in light. In addition, T Leo is very bright and equatorial -- so all of us can do it, and it's great for the small-scopers who have trouble with the fainter stars. Could you let me (and everyone; send to cba-news) know if you have gotten or expect to get time series on this star? I'm somewhat reluctant to declare a campaign now for fear that our coverage will be too sparse -- but if at least three of us are planning to do it, then I think we should all pitch in. As some of you know, the April PASP will be a special issue on CVs, including an updated Downes-Shara catalog. We'll send it out to all nonprofessional CBAers. So the star I am really plugging for all northerners is DW UMa. But I'm also hoping to get a campaign going on SW Sex (1012-03), which is now in good position for obervers everywhere. If nobody salutes I'll abandon this star, since our investment so far is very small; but I thought I would keep trying. Finally there is V803 Cen. From March 25 through April 19 we have telescopes in South Africa and Chile scheduled for intensive observation of this guy. Snapshot observations before and after this, and in a perfect world *time-series* photometry, would be of great help. Even more finally, there is AH Eri. We've been waiting all season for an eruption, and it finally happened. It's late enough that each observer can get only brief runs, but by using several longitudes we can probably solve the period-finding problems. The star is of great interest because it may contain a magnetic white dwarf in a dwarf nova binary, an awfully rare beast. There has never been any time-series photometry in outburst. See what you can get, this could be sensational (to those of us who care). It was 12.1 yesterday, I haven't the foggiest idea how long the eruption will last. joe  From jop at astro.columbia.edu Sat Mar 1 01:49:54 1997 From: jop at astro.columbia.edu (Joe Patterson) Date: Sat, 1 Mar 1997 01:49:54 -0500 Subject: (cba:news) stars of march Message-ID: <199703010649.BAA29252@tristram.phys.columbia.edu> Dear CBAers, March 1, 1997. OK, I have the S. African mail link set up now. You can reach me at jop at astro.columbia.edu. That's the preferred address for letters, whereas Columbia is still preferred for data. But either is fine. We've just finished a mini-campaign on BH Lyn and DW UMa. One of those full-moon specials, sorry about that. Weather at all stations ranged from average to very poor, so our haul was pretty thin. But we got enough to close the books happily on BH Lyn for the observing season. DW UMa continues to be of extraordinary interest, and I certainly hope you make friends with this excellent star. We will be working on it as the prime target for many (most) of us for the next six weeks. Now there's still EG Cancri. Still superhumping a couple of weeks ago at magnitude 17.4. Now probably a little fainter; the Ouda photometry placed it at 17.85. Keep close watch for further echoes. I think the "star of the week" folks have turned away from it, and the likelihood that humans will see another echo is not great (the echo only lasts ~1 day). So let's us do our part. Even if you can't get time series, snapshot photometry would be very useful (including upper limits). (Warren, this is a good target for your occasional potshots.) Which brings us to... er, the star of the week. Namely, T Leo, back in superoutburst after about 4 years. Until this Xmas, I would've said it was "just another SU UMa star", with Porb and Psh known, so why bother? The reason is: ECHO OUTBURSTS. EG Cnc may be the king of echo outbursts, but T Leo has flung a few at us in the past, and because it is the brightest of the known echoers, it could provide crucial information on just what are these strange surges in light. In addition, T Leo is very bright and equatorial -- so all of us can do it, and it's great for the small-scopers who have trouble with the fainter stars. Could you let me (and everyone; send to cba-news) know if you have gotten or expect to get time series on this star? I'm somewhat reluctant to declare a campaign now for fear that our coverage will be too sparse -- but if at least three of us are planning to do it, then I think we should all pitch in. As some of you know, the April PASP will be a special issue on CVs, including an updated Downes-Shara catalog. We'll send it out to all nonprofessional CBAers. So the star I am really plugging for all northerners is DW UMa. But I'm also hoping to get a campaign going on SW Sex (1012-03), which is now in good position for obervers everywhere. If nobody salutes I'll abandon this star, since our investment so far is very small; but I thought I would keep trying. Finally there is V803 Cen. From March 25 through April 19 we have telescopes in South Africa and Chile scheduled for intensive observation of this guy. Snapshot observations before and after this, and in a perfect world *time-series* photometry, would be of great help. Even more finally, there is AH Eri. We've been waiting all season for an eruption, and it finally happened. It's late enough that each observer can get only brief runs, but by using several longitudes we can probably solve the period-finding problems. The star is of great interest because it may contain a magnetic white dwarf in a dwarf nova binary, an awfully rare beast. There has never been any time-series photometry in outburst. See what you can get, this could be sensational (to those of us who care). It was 12.1 yesterday, I haven't the foggiest idea how long the eruption will last. joe  From jop at astro.columbia.edu Mon Mar 3 10:46:07 1997 From: jop at astro.columbia.edu (Joe Patterson) Date: Mon, 3 Mar 1997 10:46:07 -0500 Subject: (cba:news) call off the dogs Message-ID: <199703031546.KAA02744@tristram.phys.columbia.edu> Flash. AH Eri looks boring. Take action appropriate for stars which are both poorly placed and boring. The northern skies belong to UMa. joe From jop at astro.columbia.edu Mon Mar 10 14:28:22 1997 From: jop at astro.columbia.edu (Joe Patterson) Date: Mon, 10 Mar 1997 14:28:22 -0500 Subject: (cba:news) the dwarf novae strike again Message-ID: <199703101928.OAA13192@tristram.phys.columbia.edu> Dear CBAers, The DW UMa campaign is goin' good. Keep up the good work. I heard from Brian Warner a couple hours ago that he has gotten 7 straight nights on T Leo in superoutburst. And I believe that Lasse Jensen and Tonny Vanmunster got some coverage slightly before that. All well endowed with our favorite bumps 'n wiggles. So we *have* managed to get good coverage, despite my earlier hand-wringing. And therefore we should now promote T Leo to a high-priority target. By following it intensively for another 7-10 days, we will have a long and dense time series for analysis. And with an equatorial and relatively bright star, everyone can play. Brian is going off the star as of tonight, so please jump in and assume humanity's burden to follow it. Pay no attention to any allegations that it has "returned to quiescence", because the star is (in my opinion) more interesting than ever in the aftermath of superoutbursts, especially if it "echoes" as has happened in the past. Meanwhile, we're getting ready for a major southern campaign on V803 Cen. Australites take note, I'll write soon about it. Joe  From jk at cbastro.org Tue Mar 11 18:12:02 1997 From: jk at cbastro.org (Jonathan Kemp) Date: Tue, 11 Mar 1997 18:12:02 -0500 (EST) Subject: (cba:news) CCD photometry software for ST-7 Message-ID: Hi folks, I must have been sleeping when this one entered my mailbox, so I apologize for not passing it along sooner. Kato and the Ouda folks have amended their reduction software to handle ST-7 produced images and automate large portions of the reduction process. The package looks particularly appealing and I encourage you guys to take a look at it. I don't know exactly how applicable it is to ST-6-produced frames, as I realize some of you currently have that SBIG camera version. If you have any experiences or thoughts on this package, please let me know. Since many of you may not be familiar with or have nearby the software to decompress lzh files, a zipped file (redst7.zip) is available at ftp://tristram.phys.columbia.edu/pub/cba/utilities/vsnet/redst7.zip. Jonathan > ---------------------------------------------------------------------- > > CCD photometry software for ST-7 > > ---------------------------------------------------------------------- > > (vsnet 991) > > After Maurizio's request, I have placed a CCD aperture photometry > software for ST-7 (probably works with other CCDs after necessary > modifications of parameters) in the VSNET ftp/WWW. The package was > first made publicly available via the Japanese BBS NIFTY-Serve FSPACE > (Ooruri is my handle name there, the name of a Japanese bird :-). This > online manual is a translation of the corresponding Japanese document. > > ftp://ftp.kusastro.kyoto-u.ac.jp/pub/vsnet/others/prog/DOS/redst7.lzh > > The files are compressed using LHA. > > Automatic Photometry Package for ST-7 (redst7.lzh) > > program by Ooruri (T. Kato) > Internet: tkato at kusastro.kyoto-u.ac.jp > > This program performs automatic reduction (preprocessing and aperture > photometry) of CCD images. The program is adapted especially for SBIG > ST-7 CCDs, after some revision from the original version used at Ouda > Station, Kyoto University. The program handles "low resolution" and > "full frame" FITS images of ST-7 taken using CCDOPS with a prescribed > (see below) imaging procedure. This program automatically produces an > observational log, performs combination of flat-field images, dark > subtraction, flat-fielding, detection and aperture photometry of > stars. > > Environment required: DOS compatibles with CPUs 80386 or later > > << How to install >> > > 1) Uncompress (lha e redst7) all files in an appropriate directory and > add a PATH to this directory. 'sort.exe' included here can be > substituted by the DOS one. > > 2) Set the following environmental variables. > > DATA, DOUT, DDRV: should point the drive (not directory) name to store > images > RAM: should point the drive name of the ram disk. In case without a ram > disk, set this variable to point another drive (for temporay images) > different than what the environmental variable DATA points. > (The current directories in these drives are used.) > > PMDETCFG: the file name (full path name) of the photometry parameter. > An exmaple 'st7.cfg' is included. > > A typical settings may be like: > > set data=b: > set dout=b: > set ddrv=b: > set ram=e: > set pmdetcfg=b:\ccd\st7.cfg > > 3) For computers other than NEC PC-9801 and compatibles, replace > chshow.exe with a dummy program or delete it. This program is a > graphical quick look viewer severely dependent on NEC machines. > > << CCD imaging procedure >> > > Precautions before using this system. > > 1) Save images in the FITS format. (There may be a possibility of > different FITS header format depending on the version of CCDOPS. This > program assumes the header size of 5760 bytes, necessary keywords > DATE-OBS and UT. When your CCDOPS does not fit this requirement, > consider a new version or write a conveter program). Always take > images in 'no dark' mode (take dark and object frames separatedly). > > 2) The program is confirmed to work under the combination of ST-7, > full frame images and low resolution (3x3 binning). Might not work in > other combinations. For photometric purposes, use "non-ABG" CCDs. > > 3) File names for flat-field images (twilight etc.) should begin with > 'FLAT' (flat000.st7 etc.). Be sure flat-field images are not > saturated. In practice with CCDOPS, display a histogram and take 10 > images or more with average counts of 10000. When taking the twilight, > swicth off the telescope drive. > > 4) Dark frames should begin with 'DARK' (dark000.st7 etc.). Take dark > images of the same exposure time as the object frame. It is not > necessary to take dark frames for every object frame, but when you > change the object exposure time, always take a set of dark frames of > exposures before and after the change. Remember to take dark images > before and after taking flat-field images. > > 5) The program can handle the automatic exposure sequence of CCDOPS. > > << How to use the program >> > > 1) Copy all files of a night to an appropriate directory under the > drive pointed by the DATA environment variable. Set this directory to > the current. Please remember to save raw images to other media before > running the program. The program will make changes to files. > > 2) Execute 'totoday'. This program produces the file todayobs.dat, and > renames image files to 'ST?????.IMG'. > > Note 1) This programs checks FITS files in the directory. Do not place > FITS files other than the data for processing. > Note 2) Some version of CCDOPS has a dating bug when crossing 0h local > time. If the date is not properly counted, edit todayobs.dat > so that todayobs.dat reflects the proper time series. > > 3) Execute 'redst7'. This program first performs combination of > flat-field images (stars will be removed), and stores the result to > flat.inf and *.flt files. The program next performs star detection and > photometry of all object images and stores the result to ST?????.VCH. > > 4) You may also get a de-biased and flat-fielded image of a certain > image simply by executing 'calib fname' (such as calib ST00001). This > procedure stores the processed image as fname.cal. The resultant image > is a 16-bit binary without a header. > > For further discussion, use vsnet-chat mailing list (Japanese readers > can also use NIFTY-Serve FSPACE forum). In order to share information, > the author may not respond to private queries. > > Regards, > Taichi Kato > > [Image] Other programs on the VSNET WWW > > ---------------------------------------------------------------------- > > [Image] Return to HomePage > > [Image] Return to Powerful Manager's page > > ---------------------------------------------------------------------- > Burning Daisaku.. > > vsnet-adm at kusastro.kyoto-u.ac.jp[Image] From jop at astro.columbia.edu Wed Mar 12 03:01:22 1997 From: jop at astro.columbia.edu (Joe Patterson) Date: Wed, 12 Mar 1997 03:01:22 -0500 Subject: (cba:news) old stars, new stars Message-ID: <199703120801.DAA16667@tristram.phys.columbia.edu> Hi CBAers, Long "target star" letter comin' up. Here's the summary. DW UMa. Turn out the lights, the party's over. Was fun while it lasted, but let's move on. EG Cnc. Bob Fried's data shows that it's definitely still humping (with 0.3 mag amplitude) at mag 18. This is awfully enticing. But we have very, very little data on it recently. Can you possibly help us with this? Star's faint but amplitude's big! T Leo. Back "at minimum" but still bright enough to do (15), and a potential echoer. Let's go for at least another week. AM CVn. Mag 14.1 and always pulsing with 525 s. Easy target, let's start accumulating pulse timings. EC1533-1403. Mag 13.6 and always pulsing with 1119 s. Also easy, good morning target and let's get goin'. V803 Cen. Main southern target for our South African run March 25- April 14. Snapshots of great interest too. joe From jk at cbastro.org Thu Mar 13 20:53:46 1997 From: jk at cbastro.org (Jonathan Kemp) Date: Thu, 13 Mar 1997 20:53:46 -0500 (EST) Subject: (cba:news) observing materials and such Message-ID: Hi CBAers, Within the next two days I'll make charts available for the following stars at the CBA web site (GIF, PS, & PS.GZ as usual): AM CVn, CP Eri, CR Boo, EC 1533, HS Vir, LX Ser, RX 1940, Ser 1, & T Leo If you prefer hard copies of the charts (these, or the entire collection which will number about 30 or 35), please let me know shortly as I leave Saturday afternoon for 6.5 weeks. I have copies of Duerbeck available upon request and I'd be happy to send you one if you don't already have one and would like one. Several of you have mentioned a desire to have the Palomar-Green survey since so many of our objects are to be found in that survey. I should make copies of it available upon request, but do realize that every chart is but a single square inch of often very poor contrast with the blue object marked (apparently) somewhat hastily by hand with a pen. I don't necessarily recommend it except for die-hards with a mighty good magnifying glass within arm's reach. Any nonprofessionals who don't yet have a copy of Downes & Shara, or the papers on northern secondary stars by Misselt and by Henden & Honeycutt, and would like one or all should drop me a note requesting them. As I believe Joe said earlier, we plan to have copies of the new catalog by Downes, Webbink, & Shara available in the near future. The CBA Reader is prepared and will hopefully be mailed to all nonprofessional CBAers within the next 2 days. It will include lots of interesting stuff on CVs, CCDs, and other items of interest. Let me know your thoughts on this when you get it! Jonathan From jop at astro.columbia.edu Tue Mar 18 02:40:34 1997 From: jop at astro.columbia.edu (Joe Patterson) Date: Tue, 18 Mar 1997 02:40:34 -0500 Subject: (cba:news) Equinox! Message-ID: <199703180740.CAA03836@tristram.phys.columbia.edu> Dear CBAers, March 18, 1997. We've just finished a very dense stretch of data on DW UMa, I think 18 of 20 straight days, with multiple longitudes represented. I haven't seen all of it yet, but I've seen most of it, and it's enough to convince me that the DW UMa campaign should be closed. Here are three reasons. One, we did the best job we could. It's unlikely that we will do better or as well in the future, with more divided loyalties. Two, we're now up to ~400 hr of coverage (counting last year). That's my rule of thumb borderline for feeling that we've gotten all there is to get out of the star. Three, I've been disappointed by this year's superhump. Weaker than last year, at a significantly different period, and probably less coherent too. A sufficiently poor clock that it is hard to follow from night to night (whereas it was a breeze last year). Not the Rosetta Stone that I had hoped. Add 'em up, and I think DW UMa should be gracefully retired. I'll be happy to send the merged light curve to anyone who's interested (though I think there are about 4-5 runs still not included). So what's on the marquee now? For the coming weeks, there are southern stars taking center stage. We have three straight weeks of South Africa time (March 25-April 14), and ten days of Chile time (April 9- 18). So naturally, right about now, we are tremendously interested in our (few but valued) Australasian friends! A prime target which everyone can get (except the northern Europeans I guess) is EC1533-1403. This star is reliably magnitude 13.6, and it superhumps away at a period of 1119 s. Lovely for time series. Still slightly early in the season, but definitely important to do now. Good for small telescopes to track the slowly wandering superhump, and for the bigger ones to detect fine structure (if any) in the main signal. V803 Cen (1323-42). Prime southern star for this three-week spell, assuming it does not "go south" (uh... north?) on us by diving into an extended low state. T Pyx (0900-32). This will be our early-evening target from South Africa. At magnitude 15.6 and with that dec and a small hump amplitude (0.07 mag), it is probably out of reach for all CBAers. But the Arizonans, Cap'n Bob and Dave West, are just possible. Alternatively, there are Chileans reading this. Are you there, Thomas? Finally, there's V485 Cen. Definitely a fishing expedition. Haven't seen it yet this year (usually at 18-19 I think), but I wanna keep looking in case it erupts. Thomas, can you tell us more about this star? You seem to be the only one who really knows anything about it. What about the borealites? I recommend AM CVn and EC1533 as the stars for prime coverage in the next two months. Long time series will bring much happiness. CBA charts available at the Web site and by mail if requested (maybe you got 'em already?). If you don't like the dec of EC1533, try LX Ser, another probable SW Sexer on the immediate menu. We need some pilot runs on Mister LX to decide whether to promote him or not. As always, we enormously prefer long time series. But actually quite short time series can be useful for AM CVn and EC1533, since their periods are so short (525 and 1119 s). I've found that two hours will often give an acceptable pulse timing, though longer is certainly much better. Happy Spring, oops March, Equinox in two days. My best address for correspondence remains jop at astro.columbia.edu, but data is better sent to Columbia. joe  From jop at astro.columbia.edu Tue Mar 18 02:40:34 1997 From: jop at astro.columbia.edu (Joe Patterson) Date: Tue, 18 Mar 1997 02:40:34 -0500 Subject: (cba:news) Equinox! Message-ID: <199703180740.CAA03836@tristram.phys.columbia.edu> Dear CBAers, March 18, 1997. We've just finished a very dense stretch of data on DW UMa, I think 18 of 20 straight days, with multiple longitudes represented. I haven't seen all of it yet, but I've seen most of it, and it's enough to convince me that the DW UMa campaign should be closed. Here are three reasons. One, we did the best job we could. It's unlikely that we will do better or as well in the future, with more divided loyalties. Two, we're now up to ~400 hr of coverage (counting last year). That's my rule of thumb borderline for feeling that we've gotten all there is to get out of the star. Three, I've been disappointed by this year's superhump. Weaker than last year, at a significantly different period, and probably less coherent too. A sufficiently poor clock that it is hard to follow from night to night (whereas it was a breeze last year). Not the Rosetta Stone that I had hoped. Add 'em up, and I think DW UMa should be gracefully retired. I'll be happy to send the merged light curve to anyone who's interested (though I think there are about 4-5 runs still not included). So what's on the marquee now? For the coming weeks, there are southern stars taking center stage. We have three straight weeks of South Africa time (March 25-April 14), and ten days of Chile time (April 9- 18). So naturally, right about now, we are tremendously interested in our (few but valued) Australasian friends! A prime target which everyone can get (except the northern Europeans I guess) is EC1533-1403. This star is reliably magnitude 13.6, and it superhumps away at a period of 1119 s. Lovely for time series. Still slightly early in the season, but definitely important to do now. Good for small telescopes to track the slowly wandering superhump, and for the bigger ones to detect fine structure (if any) in the main signal. V803 Cen (1323-42). Prime southern star for this three-week spell, assuming it does not "go south" (uh... north?) on us by diving into an extended low state. T Pyx (0900-32). This will be our early-evening target from South Africa. At magnitude 15.6 and with that dec and a small hump amplitude (0.07 mag), it is probably out of reach for all CBAers. But the Arizonans, Cap'n Bob and Dave West, are just possible. Alternatively, there are Chileans reading this. Are you there, Thomas? Finally, there's V485 Cen. Definitely a fishing expedition. Haven't seen it yet this year (usually at 18-19 I think), but I wanna keep looking in case it erupts. Thomas, can you tell us more about this star? You seem to be the only one who really knows anything about it. What about the borealites? I recommend AM CVn and EC1533 as the stars for prime coverage in the next two months. Long time series will bring much happiness. CBA charts available at the Web site and by mail if requested (maybe you got 'em already?). If you don't like the dec of EC1533, try LX Ser, another probable SW Sexer on the immediate menu. We need some pilot runs on Mister LX to decide whether to promote him or not. As always, we enormously prefer long time series. But actually quite short time series can be useful for AM CVn and EC1533, since their periods are so short (525 and 1119 s). I've found that two hours will often give an acceptable pulse timing, though longer is certainly much better. Happy Spring, oops March, Equinox in two days. My best address for correspondence remains jop at astro.columbia.edu, but data is better sent to Columbia. joe  From jop at astro.columbia.edu Sun Mar 23 21:42:05 1997 From: jop at astro.columbia.edu (Joe Patterson) Date: Sun, 23 Mar 1997 21:42:05 -0500 Subject: (cba:news) crabber redux Message-ID: <199703240242.VAA06470@tristram.phys.columbia.edu> Dear CBAers, March 23, 1997. I know it's a broken record, but... Our old friend EG Cancri is *still* pumping out large-amplitude photometric waves at some period close to the old superhump period (86 min). But we are just not getting enough data to define the period sufficiently (orbit? common superhump? negative superhump? some combination?). I know most of you are plenty averse to working so faint (about 18.2), but dig deep in your heart for this one, folks. The raw light curve may *look* ugly, but the scientific return is very great. If it's an orbital modulation, then it will give us Porb and enable us to put EG Cnc in its proper place, whatever that may be, in the family of CVs and superhumpers. If it's the old superhump, why, it's by far the most enduring signal of this type among the SU UMas. Not knowing is agony. The signal has a quite large amplitude, 0.3 mag. But the star is awfully faint and the runs are a little short these days (<0.2 d). So we have a daily alias problem. The USA observers are usually our strongest node, and I beg them to keep faith on this star when conditions permit. Longish integrations are fine, since the activity we care about it is somewhere near 86 min. Jonathan and I will make it our top priority in the early evening from South Africa during March 27-31. I believe that a single matched set of observations from such different longitudes on the same night will decisively settle the alias problem. But it's a very tough observation from South Africa. So I'm really, REALLY begging our friends at Wise and Ouda observatories for help with this! Well that's the story. My knees are getting bloodied. Think "white light" for such a faint star. * * * * * On to the bread and butter... For northerners, Lasse and Dave West have started the season's coverage on AM CVn and LX Ser. Both 14th mag and likely to be prime, excellent CBA targets for a couple months to come. AM CVn is a sure winner but could bore you somewhat because all the action is in the 0.02 mag signals at 9 and 17 min. LX Ser is more speculative but more entertaining, since it throws a deep eclipse at you. For southerners, V803 Cen is the star of the month. This seems to have low states around 17, high states around 13, and "cycling states" where it moves back and forth on a timescale <1 day. Very much like CR Boo, last year's prima ballerina. It's top priority during our 21-night observing run in South Africa (on the SAAO 0.75 m, starting March 25), and our 10-night run in Chile (CTIO 0.9 m, starting April 9). If the star is not stuck in a low state, then our friends in Australia and New Zealand can fill in that gap in our light curves and give us close to 24-hr coverage. It's a dream but worth staying focussed on! The star also has a 27 minute periodic signal - plenty of photometric action in all brightness states. Finally there's EC1533-1403. The major campaign still lies ahead, but worth a get-acquainted visit some chilly morning. Or an excellent choice for out-and-out southerners right now. Magnitude 13.6 and a handsome 19 minute superhump at 0.05 mag. * * * * * Some of you know that the NY Times ran a feature on the CBA March 18. Kinda warm and fuzzy. It was nice to see it, and augurs well for our future prospects in backyard research. Some of you also know that we had some success with grant support, from the NSF and the Research Corporation. That was mighty nice to see too, and will keep the toys flowing for a while. joe  From jop at astro.columbia.edu Sun Mar 23 21:42:05 1997 From: jop at astro.columbia.edu (Joe Patterson) Date: Sun, 23 Mar 1997 21:42:05 -0500 Subject: (cba:news) crabber redux Message-ID: <199703240242.VAA06470@tristram.phys.columbia.edu> Dear CBAers, March 23, 1997. I know it's a broken record, but... Our old friend EG Cancri is *still* pumping out large-amplitude photometric waves at some period close to the old superhump period (86 min). But we are just not getting enough data to define the period sufficiently (orbit? common superhump? negative superhump? some combination?). I know most of you are plenty averse to working so faint (about 18.2), but dig deep in your heart for this one, folks. The raw light curve may *look* ugly, but the scientific return is very great. If it's an orbital modulation, then it will give us Porb and enable us to put EG Cnc in its proper place, whatever that may be, in the family of CVs and superhumpers. If it's the old superhump, why, it's by far the most enduring signal of this type among the SU UMas. Not knowing is agony. The signal has a quite large amplitude, 0.3 mag. But the star is awfully faint and the runs are a little short these days (<0.2 d). So we have a daily alias problem. The USA observers are usually our strongest node, and I beg them to keep faith on this star when conditions permit. Longish integrations are fine, since the activity we care about it is somewhere near 86 min. Jonathan and I will make it our top priority in the early evening from South Africa during March 27-31. I believe that a single matched set of observations from such different longitudes on the same night will decisively settle the alias problem. But it's a very tough observation from South Africa. So I'm really, REALLY begging our friends at Wise and Ouda observatories for help with this! Well that's the story. My knees are getting bloodied. Think "white light" for such a faint star. * * * * * On to the bread and butter... For northerners, Lasse and Dave West have started the season's coverage on AM CVn and LX Ser. Both 14th mag and likely to be prime, excellent CBA targets for a couple months to come. AM CVn is a sure winner but could bore you somewhat because all the action is in the 0.02 mag signals at 9 and 17 min. LX Ser is more speculative but more entertaining, since it throws a deep eclipse at you. For southerners, V803 Cen is the star of the month. This seems to have low states around 17, high states around 13, and "cycling states" where it moves back and forth on a timescale <1 day. Very much like CR Boo, last year's prima ballerina. It's top priority during our 21-night observing run in South Africa (on the SAAO 0.75 m, starting March 25), and our 10-night run in Chile (CTIO 0.9 m, starting April 9). If the star is not stuck in a low state, then our friends in Australia and New Zealand can fill in that gap in our light curves and give us close to 24-hr coverage. It's a dream but worth staying focussed on! The star also has a 27 minute periodic signal - plenty of photometric action in all brightness states. Finally there's EC1533-1403. The major campaign still lies ahead, but worth a get-acquainted visit some chilly morning. Or an excellent choice for out-and-out southerners right now. Magnitude 13.6 and a handsome 19 minute superhump at 0.05 mag. * * * * * Some of you know that the NY Times ran a feature on the CBA March 18. Kinda warm and fuzzy. It was nice to see it, and augurs well for our future prospects in backyard research. Some of you also know that we had some success with grant support, from the NSF and the Research Corporation. That was mighty nice to see too, and will keep the toys flowing for a while. joe  From jop at astro.columbia.edu Sun Mar 30 17:17:15 1997 From: jop at astro.columbia.edu (Joe Patterson) Date: Sun, 30 Mar 1997 17:17:15 -0500 (EST) Subject: (cba:news) AQ CMi outburst Message-ID: <199703302217.RAA19905@tristram.phys.columbia.edu> G'day CBAers, My reply to Tonny's query re AQ CMi is that this star doesn't deserve the coverage now. Last year's coverage was not that great, but we did observe humps on 7 consecutive nights, giving a quite adequate baseline for defining the period. There are more subtle issues which our coverage wouldn't address, but they would require very great coverage, which is probably unfeasible this late in the season. I'd recommend AM CVn as the top priority target these days (since few observers can do EG Cnc), with the 15-hr boys (EC1533-14 and LX Ser) also quite yummy. Pretty bad weather in South Africa this week! But it's a 3-week run. Onward through the fog. joe