From jop at astro.columbia.edu Sat Dec 3 07:14:45 2005 From: jop at astro.columbia.edu (Joe Patterson) Date: Sat, 3 Dec 2005 07:14:45 -0500 (EST) Subject: (cba:news) december stars Message-ID: Dear CBAers, There's lots to report... But you're not gonna like it. I'm always reluctant to tout the faintest stars on our program as the most interesting... since these stars produce the noisiest light curves, and in general also lack the headline glamor of ERUPTIONS. But last month and this, the best targets have been a couple of bookend stars - south and north at approximately 2335+/-39 and magnitude 16.5 - which lack the panache of the glamor boys of past campaigns. But the scientific impact of this year's data is likely to be very, very great. The northern star is HS2331+39 ("And"), targeted by Tom Krajci and Lew Cook. The data has been very good despite the star's faintness, refining Porb and proving a quiescent superhump. But we still have no significant data from longitudes outside the western USA, so we have 24-hour aliasing uncertainties. Any help from Europe forthcoming? If the weather stays good in the western USA, even a little coverage from Europe will entirely solve the problem; if it gets cloudy here, well, then a somewhat bigger effort is needed. And the southern star is BW Scl. Ditto all around - same magnitude, same position with declination flipped, same place in CV evolution (last-chance saloon), same scientific result (quiescent superhump), same analysis problem (aliasing). Pretty good weather now in NZ, where Bob Rea and Grant Christie are working hard on it, and greatly in need of coverage from other longitudes. Even Australia would be mighty good! My top recommendation for northern post-midnight coverage is FS Aur, with "Tau 2" (0400+06) as a close second choice. In the south. I have three recommendations. I'd like to promote Tau 2 as first choice - since with S and N coverage we can actually span the globe (separately we never manage that, almost always lacking Asia in the north and South America in the south). But for 200 years (or more) southern astronomers have been mighty reluctant to look north - maybe on the same general theory that motivates people to commit crimes in their own neighborhoods. So if your telescope is reluctant to point north, I recommend WX Hyi and VW Hyi. We'll be undertaking a series of studies of dwarf novae at quiescence, and these are awfully good stars to start with! Finally I'd like to emphasize again that we'll have a CBA meeting coincident with (and within) the SAS (IAPPP-West) meeting in Big Bear Lake, CA. More or less the same place as Big Bear City, in case you're trying to locate it. You don't have to register, commit, pay, etc. for the CBA component, but you do have to register normally for the SAS meeting. You can do that on their website - and Jerry Foote can give you more info if you need it. There are many astronomical and recreational side-trips feasible from Big Bear, and I'll organize some (probably including one to Mt Palomar). But I also have observing time on Kitt Peak adjacent to the meeting dates... and if you have a little extra time, you might want to consider flying to Tucson and spending a coupla nights at the observatory. I'm likely to be a pretty decent tour guide - I used to do it for a living! And late May weather in southern Arizona is very, very good. Let me know your thoughts on this. joe From jop at astro.columbia.edu Thu Dec 8 16:35:50 2005 From: jop at astro.columbia.edu (Joe Patterson) Date: Thu, 8 Dec 2005 16:35:50 -0500 (EST) Subject: (cba:news) V701 Tau and FS Aur Message-ID: Dear CBAers, V701 Tau has jumped into outburst, and is showing superhumps. FS Aur climbed into its version of outburst while Tom Krajci was watching it. These are good enough for me. Let's elevate these stars to be the top northern targets! In other words, the season's gonna end for HS2331+39. It was a great season, and I believe we have enough data to solve the various period issues. Details in a few weeks. Comments on southern targets in the next day or two. joe From jop at astro.columbia.edu Fri Dec 9 15:49:54 2005 From: jop at astro.columbia.edu (Joe Patterson) Date: Fri, 9 Dec 2005 15:49:54 -0500 (EST) Subject: (cba:news) HT Cam outburst Message-ID: Dear CBAers, I hate to pile on here... considering that V701 Tau and FS Aur are now eruptive northern stars very deserving of coverage. But an HT Cam outburst is just too provocative to pass up. HT Cam is a short-Porb star that probably ought to show a genuine superoutburst eventually. Only two outbursts have been observed so far, and they were extremely brief - though of considerable interest anyway because of the 8 minute rotation clock in the system. (So watching the effect of the outburst on the periodic signal is pretty fascinating). If a long outburst develops, then... all hail HT Cam! But I think it's necessary to jump now anyway, even though the outburst will probably be brief. Maybe a good target after V701 Tau... and maybe all night long. Lotta action in the northern sky these nights! joe Here's the announcement. I don't know Maehara, but he's a *very* experienced variable-star observer. ********************************************** From: Hiroyuki Maehara Reply-To: cvnet-outburst at yahoogroups.com To: vsnet-outburst at ooruri.kusastro.kyoto-u.ac.jp, cvnet-outburst at yahoogroups.com Subject: [cvnet-outburst] HT Cam outburst Dear colleagues, HT Cam is undergoing an outburst. object YYYYMMDD(UT) mag code CAMHT 20051209.78396 12.68V Mhh.VSOLJ CAMHT 20051209.78645 12.54B Mhh.VSOLJ Regards, Hiroyuki Maehara ***************************************** From jop at astro.columbia.edu Sat Dec 10 15:33:36 2005 From: jop at astro.columbia.edu (Joe Patterson) Date: Sat, 10 Dec 2005 15:33:36 -0500 (EST) Subject: (cba:news) HT Cam Message-ID: Tonny's note pretty much establishes that the two-night HT Cam outburst is over. Again it tempts us and dashes our hopes! However... Tom's one night of coverage is one of the most interesting CV light curves I ever saw. There was a fascinating display of periodic signals. I'm going to analyze and report back in a day or two. Meanwhile, if you can observe at m=17, please do so for 1-3 more nights! We'd like to glean a little information about the post-outburst state. Admittedly it's not going to be handsome data - especially since I'd like to observe with integration times no longer than 70 s (I recommend 40-60 s). But the star has fast periods, so we need short delta-ts. Even if it looks bad, the periodic signals might still come shining through! Maybe. joe From jop at astro.columbia.edu Tue Dec 13 08:45:55 2005 From: jop at astro.columbia.edu (Joe Patterson) Date: Tue, 13 Dec 2005 08:45:55 -0500 (EST) Subject: (cba:news) new x-ray transient... Message-ID: Dear CBAers, Today's announcement smells of CBA raw meat. An AM-Her or at least a CV identification fits all facts known to date... and a long light curve will say yay or nay! joe ------------------------------------------------------------------------------ ------------------------------------------------------------------------------ The Astronomer's Telegram http://www.astronomerstelegram.org ============================================================================== ATEL #673 ATEL #673 Title: Swift/XRT detection and localization of IGR J01583+6713 Author: J. A. Kennea, J. L. Racusin, D. N. Burrows, S. Hunsberger, J. A. Nousek (PSU) and N. Gehrels (NASA/GSFC) Queries: kennea at astro.psu.edu Posted: 13 Dec 2005; 12:21 UT Subjects: X-ray, Transients At 00:00 UT on December 13th, 2005 Swift began a Target of Opportunity observation of IGR J01538+6713, a recently discovered hard X-ray transient source discovered by INTEGRAL (Steiner et al., ATEL #672). Analysis of 5ks of XRT data from this observation reveals a single point source inside the INTEGRAL 2 arcminute radius error circle at the following coordinates: RA = 01:58:18.2, Dec = +67:13:25.9 (J2000), with an estimated uncertainty of 3.5 arcseconds (90% containment). This location is 17 arcseconds from the INTEGRAL position reported in ATEL #672, and is not consistent with the position of any catalogued X-ray source. A J=11.5 2MASS catalogue object is 2.9 arcseconds from the XRT position. This object is also present in the USNO catalogue, with reported magnitudes of R=13.9 and B=15.3. We encourage optical follow-up of this location to determine if this source in the optical counterpart of IGR J01538+6713. Spectral fitting of this source is uncertain, due to low source flux. However an absorbed power-law model shows that IGRJ01583+6713 is highly absorbed, with N_H approximately 10^23 cm^-2. This absorption is in excess of the estimated galactic value of N_H is 4.7 x 10^21 cm^-1. The measured flux is approximately 1.5 x 10^-11 erg/s/cm^-2 (0.2-10 keV), uncorrected for absorption. IGR J01583+6713 does not appear to be fading during our observation. ------------------------------------------------------------------------------ Password Certification: Jamie A. Kennea (kennea at astro.psu.edu) http://www.astronomerstelegram.org/?read=673 ============================================================================== From jop at astro.columbia.edu Thu Dec 15 21:31:29 2005 From: jop at astro.columbia.edu (Joe Patterson) Date: Thu, 15 Dec 2005 21:31:29 -0500 (EST) Subject: (cba:news) X-ray transient Message-ID: OK I'm convinced... by Tom Krajci's and Bill Goff's reports of no varaiability. That may or may not eliminate the star as a suspect, but it does eliminate the star as a CBA suspect. Away with it! joe From jop at astro.columbia.edu Thu Dec 29 17:26:01 2005 From: jop at astro.columbia.edu (Joe Patterson) Date: Thu, 29 Dec 2005 17:26:01 -0500 (EST) Subject: (cba:news) New stars for 2006 Message-ID: Dear CBAers, 12/29/05 After the onslaught of final exams and letters to write, I've done the first-pass evaluation of this month's targets. And it's time for a complete revamping of the menu. HT Cam and V701 Tau were eruptive stars, and are gone. WX Hyi and VW Hyi are at quiescence; we have good hump timings and can update the ephemerides accordingly. Probably time to shift away from these stars - unless one of 'em jumps into supermax in the next week. Tau 2 seems to now be in an intermediate state - very annoying for period search, and indeed for any kind of study. Suspended temporarily. FS Aur stays viable - as it always will until we figure out its strange period structure. But the period is stable... so let's let it go till late in the season. My all-sky recommendations are two: SDSS 0407-06 ("Eri") and V1193 Ori. Both are nicely astride the celestial equator, transiting near midnight, and have reported superhump signals in their light curves. We've never seen 'em - but then again, we've never looked! We need to, in order to evaluate these important reports. Let's get all feasible continents going on this! V1193 Ori is about 14.1, an easy target. Eri is much fainter, but has nice deep eclipses to reward your efforts. And two other stars of a distinctly southern preference. There's the immortal T Pyx. We do it every year, tracking its mysterious and enormous period increase. I promise this is the last! A few weeks of timings, and the study is finished (and I'll write it up forthwith). And there's AQ Men = EC0511-7955. We've only observed that one year... but one more year, or likely just one month, will wrap up the study. And two northern stars too. Early in the night, there's "Cam" = HS0506+77. A newly discovered VY Scl star, definitely ripe for superhump search; usually at 15-15.5, but with occasional low states. And DW Cnc: a nice discovery of 2 years ago, we need to follow up (for the next month at least) to measure the long-term period change. That's the new menu. Happy observing! By the way, let me know if you're considering coming to CA for the SAS/CBA meeting in late May. joe