From jk at cbastro.org Sat Jan 4 04:19:08 1997 From: jk at cbastro.org (Jonathan Kemp) Date: Sat, 4 Jan 1997 04:19:08 -0500 (EST) Subject: (cba:news) EG Cancri Message-ID: Well, EG Cancri is popping out of its hole once again (and 4 weeks before Groundhog Day*, no less)! During a two-hour time series from Cerro Tololo, EG appears to have brightened by about 0.25 magnitudes (~13.8 to ~13.55). The stubborn fellow is certainly bright enough once again for even the small 'scope folks... Jonathan _____ * For those of you overseas, a bizarre American "holiday" involving rodents predicting the changes of seasons (more info at www.groundhog.org if you really must know). From jop at astro.columbia.edu Thu Jan 9 23:14:19 1997 From: jop at astro.columbia.edu (Joe Patterson) Date: Thu, 9 Jan 1997 23:14:19 -0500 Subject: (cba:news) changing stellart fashions Message-ID: <199701100414.XAA26025@tristram.phys.columbia.edu> Dear CBAers, Jan. 10, 1997. As most of you know, EG Cnc is continuing to light up the solstice sky with eruptions and photometric waves. The "main event" of the superoutburst ended about December 18, but since then the star has jumped back to mag 13.5 on 3 occasions (every 7 days or so; each time it falls back to about mag 16. We obtained very good coverage when the superhumps were strong (December 6-13 or so), but coverage since then has not been good. Jonathan has been observing it for a week straight at Cerro Tololo, but it's quite a strain at -30 degrees. Also, his light curves have shown only quite small wiggles. Such things considered, I'm inclined to declare the EG Cnc campaign over. Unless the star stages another full-fledged superoutburst, let's quit. Oh, and ditto for PX And. This campaign was entirely successful, yielding strong negative and positive superhumps. But evening twilight has ended it. As I stated last time, I really wanted to promote BH Lyn as the best northern target for January. I still do. But yesterday brought the news of a BZ UMa outburst; if it's a *long* outburst, it would be a very good target. (BH Lyn can wait a bit since it's not an eruptive star.) The best comp star is 2.5 arcmin west of the variable, at V = 13.77 (and unfiltered CCD mag about 13.3 I think). For the smallest telescopes, you might want to select the brighter comp star another 1 arcmin WSW. A good chart is in Downes & Shara, and the 2000 coords of BZ UMa are 8 53 44.3 +57 48 40. This is an excellent target for the smallest telescopes, and a good one for all telescopes, but be warned that most of the outbursts are short -- no betting the farm on this one. You can, however, bet the farm on BH Lyn and DW UMa, and these are the prime objects for winter observing. For the australites, we're doing campaigns on Men 1 = H0551-819 (main target) and RR Pic (back-up). We also would love snapshots and short time series on V803 Cen for the rest of the observing season (6 more months). joe  From jop at astro.columbia.edu Thu Jan 9 23:14:19 1997 From: jop at astro.columbia.edu (Joe Patterson) Date: Thu, 9 Jan 1997 23:14:19 -0500 Subject: (cba:news) changing stellart fashions Message-ID: <199701100414.XAA26025@tristram.phys.columbia.edu> Dear CBAers, Jan. 10, 1997. As most of you know, EG Cnc is continuing to light up the solstice sky with eruptions and photometric waves. The "main event" of the superoutburst ended about December 18, but since then the star has jumped back to mag 13.5 on 3 occasions (every 7 days or so; each time it falls back to about mag 16. We obtained very good coverage when the superhumps were strong (December 6-13 or so), but coverage since then has not been good. Jonathan has been observing it for a week straight at Cerro Tololo, but it's quite a strain at -30 degrees. Also, his light curves have shown only quite small wiggles. Such things considered, I'm inclined to declare the EG Cnc campaign over. Unless the star stages another full-fledged superoutburst, let's quit. Oh, and ditto for PX And. This campaign was entirely successful, yielding strong negative and positive superhumps. But evening twilight has ended it. As I stated last time, I really wanted to promote BH Lyn as the best northern target for January. I still do. But yesterday brought the news of a BZ UMa outburst; if it's a *long* outburst, it would be a very good target. (BH Lyn can wait a bit since it's not an eruptive star.) The best comp star is 2.5 arcmin west of the variable, at V = 13.77 (and unfiltered CCD mag about 13.3 I think). For the smallest telescopes, you might want to select the brighter comp star another 1 arcmin WSW. A good chart is in Downes & Shara, and the 2000 coords of BZ UMa are 8 53 44.3 +57 48 40. This is an excellent target for the smallest telescopes, and a good one for all telescopes, but be warned that most of the outbursts are short -- no betting the farm on this one. You can, however, bet the farm on BH Lyn and DW UMa, and these are the prime objects for winter observing. For the australites, we're doing campaigns on Men 1 = H0551-819 (main target) and RR Pic (back-up). We also would love snapshots and short time series on V803 Cen for the rest of the observing season (6 more months). joe  From jop at astro.columbia.edu Mon Jan 13 10:06:07 1997 From: jop at astro.columbia.edu (Joe Patterson) Date: Mon, 13 Jan 1997 10:06:07 -0500 Subject: (cba:news) january stars Message-ID: <199701131506.KAA03143@tristram.phys.columbia.edu> Dear CBAers, 1/13/97 Well, howdja like that. No sooner do I warble the praises of BZ UMa than it disappears. Bah. Those damn short outbursts. Then I chide EG Cnc as a non-performer, and Bob Fried sends me three long nights with great-looking superhumps. So much for "the experts". Take this message as replacing the one of three days ago, which turned out to be not too smart. EG Cnc is still a good target, especially if you have already built up an investment. Just how good it is depends on its eruptive history in the near future, which of course nobody knows. It is however superhumping continuously, and I think has been since December 5. In addition to the time series, multicolor photometry or spectrophotometry would be of high interest, as the star has been changing its spectral slope a lot in these "echo" outbursts that it is now flashing to the wonderment of all. Our main star this month is nevertheless BH Lyn. Alon Retter has the Wise Observatory 1-m scheduled for this star during Jan. 19-26. The Israeli weather isn't very good in January, and there's a bright moon; but with the northerly dec and the long winter nights, it's still a fine occasion to try for real round-the-world coverage. Dave Skillman and Lasse Jensen have made friends with the star already, and verified that it's waving and eclipsing and doing those fine things that we like. Go Japan and Hawaii, we're hoping! The other two SW Sexers burrowing their way into the night sky are DW UMa and SW Sex. We'll do intensive campaigns in Feb-Mar-Apr, but some morning visits now would be nice. Lasse got a long run last night on RZ LMi which showed fine superhumps. So let's have a word about this star. We got some fine data two years ago, which suggested (but did not prove) that the superhumps actually maintain phase from one superoutburst to the next. At least they did for five in a row. That would be remarkable and I wanted to study it some more. But things came up, and the project got shoved aside. Now I'm thinking about it again. The star has supermaxima just 19 days apart, so with foresight we could basically sample the superhumps of about the next six supermaxima, with no huge effort involved. Six more would make a believer out of me. If some of the bigger telescopes in our network (Wise, Ouda, CBA-East) could add in a few time series at quiescence, we could find out if the means for such good phase memory is basically superhump continuation at quiescence (which I conjecture is also true). So this is in my opinion an excellent season-long project to plug away on. Now about snapshots. Not of course a specialty of ours, but in the case of CR Boo we learned a great deal from them. There are definitely a few stars in our program which have sufficiently little known about their pattern of variability that snapshot coverage is of high value. These are: V803 Cen (dum-da-dum-dum, big target this year on all time scales!), CR Boo, HS Vir, Ser 1=PG1510+234, CP Eri, and Hya 1=PG0911-066. The three helium stars in the list aren't in Downes & Shara, who didn't like helium; so we'll get the charts prepared and posted (I think CR Boo and V803 Cen are already posted). The last three stars are usually a bit faint, so you'll need longish exposures. I realize that some CBAers are not so well set up for time series, but could contribute greatly with snapshots. Please let me know who you are! joe  From jop at astro.columbia.edu Tue Jan 14 13:51:33 1997 From: jop at astro.columbia.edu (Joe Patterson) Date: Tue, 14 Jan 1997 13:51:33 -0500 Subject: (cba:news) wonders of the solstice Message-ID: <199701141851.NAA06325@tristram.phys.columbia.edu> Couldn't resist sending you this one. An 11-hour run on BH Lyn from CBA-East last night. It's what we call in the biz a "typical" light curve. In other words, better than anything we ever saw. Protected by no copyright or any other impediment whatever. You can use this light curve in any way you want, including but not limited to the reaping of immense wealth, persecution of one's political enemies, etc. Go, Mister BH, and go, CBAers.  462.51014, 1.325 462.51082, 1.3 462.51149, 1.278 462.51218, 1.251 462.51285, 1.287 462.51352, 1.266 462.5142, 1.213 462.51487, 1.235 462.51554, 1.299 462.51623, 1.348 462.5169, 1.307 462.51757, 1.309 462.51824, 1.226 462.51892, 1.253 462.5196, 1.284 462.52027, 1.274 462.52095, 1.266 462.52162, 1.211 462.52229, 1.168 462.52296, 1.134 462.5236499, 1.159 462.52432, 1.195 462.52499, 1.315 462.52567, 1.318 462.52634, 1.33 462.52701, 1.327 462.52769, 1.338 462.52837, 1.319 462.52904, 1.369 462.52971, 1.29 462.53039, 1.311 462.53107, 1.251 462.53174, 1.189 462.53242, 1.231 462.53309, 1.25 462.53376, 1.286 462.53445, 1.221 462.53512, 1.233 462.53579, 1.211 462.53646, 1.212 462.53714, 1.122 462.53781, 1.208 462.53848, 1.208 462.53917, 1.181 462.53984, 1.201 462.54051, 1.269 462.5411899, 1.245 462.54186, 1.235 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462.83818, 1.163 462.83888, 1.193 462.83956, 1.19 462.84026, 1.2 462.84094, 1.179 462.84163, 1.17 462.84232, 1.109 462.84301, 1.086 462.8437, 1.053 462.84439, 1.12 462.84508, 1.113 462.84576, 1.073 462.84646, 1.093 462.84715, 1.131 462.84784, 1.151 462.84853, 1.113 462.84921, 1.152 462.84991, 1.101 462.8506, 1.074 462.85129, 1.038 462.85198, .977 462.85266, .985 462.85336, 1.039 462.85404, 1.069 462.85473, 1.089 462.85543, 1.029 462.85611, 1.086 462.85681, 1.117 462.85749, 1.09 462.85818, 1.061 462.85888, 1.078 462.85956, 1.049 462.86026, 1.004 462.86094, 1.032 462.86163, 1.057 462.86233, 1.031 462.86301, 1.026 462.8637, 1.103 462.86439, 1.022 462.86508, 1.034 462.86576, 1.039 462.86646, 1.026 462.86714, 1.049 462.8678399, 1.054 462.86853, 1.045 462.86921, 1.04 462.86991, .984 462.87059, .974 462.87129, .944 462.87198, .97 462.87266, .966 462.87336, .963 462.87404, .923 462.87473, .987 462.87543, 1.004 462.87611, .994 462.87681, .935 462.87749, .961 462.87818, .993 462.87888, 1.08 462.87956, 1.081 462.88026, 1.115 462.8809399, 1.126 462.88163, 1.084 462.8823299, 1.153 462.88301, 1.119 462.8837, 1.153 462.88439, 1.151 462.88508, 1.1 462.88576, 1.143 462.88646, 1.138 462.88714, 1.141 462.88784, 1.111 462.88853, 1.135 462.8892099, 1.101 462.88991, 1.111 462.89059, 1.062 462.89129, 1.044 462.89197, 1.099 462.89266, 1.139 462.89335, 1.144 462.8940399, 1.161 462.89472, 1.117 462.89542, 1.103 462.8961, 1.068 462.89679, 1.069 462.89748, 1.025 462.89817, 1.012 462.8988699, 1.02 462.89955, 1.094 462.90024, 1.115 462.90093, 1.139 462.90162, 1.184 462.9023, 1.211 462.903, 1.258 462.90368, 1.306 462.90438, 1.355 462.90506, 1.391 462.90575, 1.46 462.90644, 1.484 462.90713, 1.528 462.90781, 1.629 462.90851, 1.738 462.90919, 1.87 462.90989, 1.887 462.91057, 2.127 462.91126, 2.213 462.91195, 2.424 462.91263, 2.585 462.92089, 1.878 462.92157, 1.728 462.92226, 1.625 462.92295, 1.465 462.92364, 1.384 462.92432, 1.44 462.92501, 1.422 462.9257, 1.401 462.92638, 1.391 462.9270699, 1.416 462.92776, 1.363 462.92844, 1.338 462.9291199, 1.345 462.92982, 1.387 462.9305, 1.303 462.93118, 1.259 462.93188, 1.29 462.93257, 1.256 462.93325, 1.206 462.9339499, 1.228 462.93463, 1.17 462.93531, 1.186 462.93601, 1.244 462.93669, 1.228 462.93737, 1.236 462.93807, 1.258 462.93876, 1.236 462.93946, 1.323 462.94014, 1.25 462.94083, 1.271 462.94152, 1.313 462.94221, 1.223 462.94291, 1.333 462.9436, 1.182 462.94428, 1.229 462.94498, 1.267 462.94567, 1.252 462.94635, 1.245 462.9470499, 1.276 462.94774, 1.251 462.94843, 1.246 462.94982, 1.179 462.9505, 1.177 462.95119, 1.191 462.95189, 1.187 462.95258, 1.26 462.95326, 1.305 462.95395, 1.223 462.95464, 1.282 462.95534, 1.208 462.95602, 1.226 462.9567099, 1.374 462.95741, 1.273 462.95809, 1.306 462.95948, 1.283 462.96155, 1.217 462.96223, 1.271 462.96293, 1.301 462.96431, 1.324 462.9657, 1.261 462.96777, 1.387 462.96846, 1.346 462.96914, 1.181 From jop at astro.columbia.edu Thu Jan 16 11:37:49 1997 From: jop at astro.columbia.edu (Joe Patterson) Date: Thu, 16 Jan 1997 11:37:49 -0500 Subject: (cba:news) stars of the month Message-ID: <199701161637.LAA09583@tristram.phys.columbia.edu> Dear CBAers, Jan. 16, 1997. Well, I studied the EG Cnc data some more and see that this is probably the most interesting superhumper of all the dwarf novae. For the first two weeks, it was pretty much ho-hum, oh-yes-another-one-of- those. But now it's evident that the humps have been severely affected by the secondary outbursts that have punctuated the decline. Unfortunately this means that we need extensive coverage through these outbursts, which we're not getting. If the star continues to burp and the superhumps continue, we can probably atone for this; otherwise we'll try to join forces with some other EG Cnc observers, in order to define the waves properly. So I wanted to re-promote this star as co-equal with (or better than) BH Lyn in the coming 12-day period. We desperately need more data. Alon, I strongly think you should try to do EG Cnc as well as BH Lyn during your run coming up. With average or good weather I believe we can get enough data to solve the important 24-hr aliasing and fine- structure issues for both stars. I also recommend unfiltered operation in both cases. For BH Lyn, it's because we have a great deal of interest in the exact shape of the eclipse; that's what will constrain the shape/size of the disk. I think we need the extra counts to define the light curve better in eclipse. For EG Cnc, it's mainly because the star is 16th mag out of outburst (likely to fade further too). I recommend spinning the filter wheels once at the beginning and end of an observation, to help calibrate the magnitude levels better. Meanwhile, the Moon waxes onward. Sorry about that. Try somewhat longer exposures if the stars are too faint for you (especially the small-scopers) -- assuming the drive quality is up to snuff. Let me know what you manage to get! joe From jop at astro.columbia.edu Sat Jan 18 18:46:13 1997 From: jop at astro.columbia.edu (Joe Patterson) Date: Sat, 18 Jan 1997 18:46:13 -0500 Subject: (cba:news) flashy stars for cold nights Message-ID: <199701182346.SAA12772@tristram.phys.columbia.edu> Hello CBAers, 1/18/97 Well, Alon Retter starts his eight-night run tomorrow night in Israel, so this is our best chance for a northern-hemisphere "Whole-Earth" run on the prime targets: EG Cancri and BH Lyncis. At January 18.2 EG was at V=14.9 and dropping; I expect it to be at 15.7 tonight and about 16.1 the next couple nights. So you small-scopers out there, I imagine you'd prefer to do BH Lyn (about 14.9 out of eclipse). Do consider EG, however; the damn thing is continuing to echo and wave and generally demand attention. Tonny Vanmunster managed to get 7.5 hr on it last night, a mighty fine start on our coverage of the latest echo. Go CBAers, brave that cold and Olde Whiteface, blow all aliases to kingdom come. joe  From jop at astro.columbia.edu Mon Jan 27 20:06:40 1997 From: jop at astro.columbia.edu (Joe Patterson) Date: Mon, 27 Jan 1997 20:06:40 -0500 Subject: (cba:news) jan-feb stars Message-ID: <199701280106.UAA11874@tristram.phys.columbia.edu> Dear CBAers, 1/27/97 Well, the declared "campaign" on BH Lyn and EG Cnc largely fizzled. Bad weather and instrument down time struck many nodes of the CBA at once, and this particular interval (Jan 19-26) actually was a time of sparse observation. Sometimes you get the bear... But actually as data dribbled in from the preceding 10 days, I see that we did quite well on both stars during this earlier interval. Here's a summary of what we learned. BH Lyn. As with PX And (and about 10 other stars in the sky), this star too has simultaneous positive and negative superhumps. The positive guys are slightly stronger (0.12 versus 0.08 mag full amplitude), reversed from PX And. The eclipses are much deeper, giving a better opportunity for using the changing eclipse shape to diagnose the changing shape of the disk -- if our data are of sufficient quality. EG Cnc has continued to do its rather amazing thing. It is certainly the king of echo outbursts, whatever they are. It also flashes the most confusing superhumps I've seen. On two occasions it seemed to break off and start waving at a much different period, then return to its familiar 0.0604 d period. Will we understand this behavior? I dunno. Certainly we'll have a better chance if we can increase our vigilance. So keep after this star with relentless time series, the longer the better. It's now spending most of its time around magnitude 16-16.5; most of you will find this tough, but the wave does have a 0.2 mag amplitude at this brightness level, so it may well be feasible. Bob Fried has gotten excellent light curves at this magnitude with his 16-inch. What of the future on these guys? Well, I'd rate EG Cnc the highest priority target. I'm not sure we'll be able to decipher those strange waves, but we might, if you can mount a big effort now. The star is just as attractive (if not more so) at 16th mag as at 13th! BH Lyn is also a good target, we should keep after it through Feb 22, when a second Wise Observatory run ends. But it's time to make friends with new stars also. The other SW Sex stars available now are DW UMa (1030+59) and SW Sex (1012-03). Dave Skillman saw very strong negative superhumps in the former last spring, and Lasse Jensen has started the 1997 coverage which shows them still present. (With a 10-inch, by the way.) A very good time to start your coverage of DW UMa, really a pretty easy star to do because of the sky position, large-amplitude wave, eclipses, and lack of flickering. We'll concentrate on SW Sex in March when we have scheduled time in South Africa (also, I think southerners might start the coverage earlier). Now let's talk about... SNAPSHOTS. We don't usually mess with these much, but they prove awfully useful for stars where we really don't know the basic eruption timescales yet. Here are the stars where we want an ongoing program of snapshot magnitudes: CR Boo, HS Vir, PG1510+234 = Ser 1, V803 Cen, and EG Cnc. Each of these stars shows very rapid photometric activity, so a high density of observation (e.g. more than one/night) is highly warranted. Good luck, and keep me informed as to what coverage you manage to get. Lemme know if you'd like light curves of any of these stars. joe P.S. By the way, despite Brian Skiff's recent fire-and-brimstone denunciation in the VS-NET of unfiltered photometry, unfiltered is definitely the best way to go for studies of periodic effects in stars of this magnitude (13-16). Even the Johnson and Cousins VRI filters, usually called "broadband", transmit only ~10% of the total unfiltered light available to the CCD. That's not good enough. Most of us have small telescopes and cannot afford such a severe loss of light. Longer exposures can partially compensate, but are limited by the quality of the telescope drive and by the (frequent) desire to maintain good time resolution. I'll write more completely on this subject later; but for the present I just wanted to chip in with this *emphatic* endorsement of unfiltered light for our programs.