From jop at astro.columbia.edu Fri Jul 3 11:43:36 1998 From: jop at astro.columbia.edu (Joe Patterson) Date: Fri, 3 Jul 1998 11:43:36 -0400 (EDT) Subject: (cba:news) summer superhumps Message-ID: <199807031543.LAA09228@tristram.phys.columbia.edu> Dear CBAers, July 3, 1998. Back from 2 cloudless weeks in AZ, and the ASP meeting in Albuquerque. As I mentioned before, the next ASP meeting (nominally July 1-7, 1999) will be in Toronto and will have amateur-professional collaboration as its main theme. I would like to use this to lure as many of you as possible and have an official CBA workshop there. Stan tells me that this conflicts with an important NZ meeting, which I also hoped to attend. I don't know what exactly will come of that, but the dates are immutable... so there it is. The campaign on RX1940-10 = V1432 Aql is going well, thanks primarily to Captain Bob. The two periods in this star beat together with a 50- day cycle, leading to the expectation that the eclipse waveform will change with this period. So our main goal is to get full coverage of the cycle, meaning no gaps exceeding 2 days. It's proceeding well so far. If the Arizona monsoon rains ever arrive, which they nearly always do, then we'll need lots of help from other stations. There's another star I'd like to tout most heavily right now. Dave Harvey has started the season on V1315 Aql = KPD 1911+1212. It's perfectly placed right now, and his data show fairly strong superhumps, as well as the obvious and well-known eclipses. But his data are aliased and need help from other longitudes. Anyone out there with an exotic longitude, we need ya bad! I think Dave's comparison star is the bright star near the edge of the Downes & Shara chart, about 3.5 arcmin SSW from the variable. But you can use another if more convenient, as long as you tell me which. Most of the observations will be (as usual) in unfiltered light with an ST-7, but we can transform as long as the effective wavelength is not tremendously different. We're on a streak with this star right now, so observations in the next few days are of even greater value since they will have great leverage over alias-breaking. Meanwhile, for the smallscopers, Jerry Gunn and Tonny Vanmunster have gotten the V603 Aql season off to a good start. During the upcoming full moon period, this would surely be the best target for all. Finally, we have been observing the new X-ray transient at 21 hrs -5 degrees. It's about 17, too faint for most, but we certainly would love to get help from exotic longitudes on this guy! All these stars are hemisphere-neutral. Australites take note. Joe From jop at astro.columbia.edu Thu Jul 23 14:16:30 1998 From: jop at astro.columbia.edu (Joe Patterson) Date: Thu, 23 Jul 1998 14:16:30 -0400 (EDT) Subject: (cba:news) The XTE 2123 watch Message-ID: <199807231816.OAA29871@tristram.phys.columbia.edu> Dear CBAers, Let's keep this watch going for at least two more days. There is some evidence that the star is entering a new state - brighter in X-rays, fainter (alas) optically. Definitely bursting. Not a target for smallscopers, admittedly. Other stars on the marquee now are V1432 Aql = RX1940-10 and V1315 Aql, and pulse timings of AO Psc, FO Aqr. Jerry Gunn has put together a very impressive streak on V603 Aql. This one remains a good target for small scopes for the next two weeks. joe From jop at astro.columbia.edu Mon Jul 27 19:24:52 1998 From: jop at astro.columbia.edu (Joe Patterson) Date: Mon, 27 Jul 1998 19:24:52 -0400 (EDT) Subject: (cba:news) estrellas de agosto Message-ID: <199807272324.TAA02060@tristram.phys.columbia.edu> Dear CBAers, July 27, 1998. Ready to ring down the curtain on AM CVn and V603 Aql -- former because of twilight, latter because Jerry Gunn's long data stream sufficiently describes its present behavior (similar to 1994 but less pronounced). Some of you southerners should get some parting shots on HP Lib; that one has another 4-6 weeks of life. That XTE star is interesting, but impossibly faint (19th) for nearly all of us. The most interesting centrally placed stars remain RX1940-10 = V1432 Aql and KPD 1911+1212 = V1315 Aql. The former has been relentlessly chased by Cap'n Bob. Keep that a'goin', it's needed to disentangle the very closely spaced periods in this star. We need to keep that campaign going through mid-September. For the latter, we need 2-3 more weeks. We've been using the comparison star near the edge of the Downes-Shara chart, about 3.5 arcmin SSW from the variable. Although V603 Aql now bows out as a small-scope target, V Sagittae comes back in. We did it last year and published the results in the April 1998 PASP. The star has attracted a lot of interest, and we should now undertake a trickier study: to find the mean light curve at its several luminosity states (actually the luminosity states span a continuum, but it would be nice to get mean light curves in bright, faint, and intermediate states). Practically this just means a whole lotta coverage over the rest of the season - only later can we figure out when it was in what state. I recommend it highly to the 8-10 inch telescope owners. Still no pulse timings on AO Psc or FO Aqr! Horrors! Very, very untrue to our mission. All are shamed. For borealites in the morning sky, our friends V592 Cas and TT Ari are back. Let's start the season propitiously on them. You aussies and kiwis out there - I promise to root for all of your international sports teams, if you could help us out on V1315 Aql. I'm having a terrible time with the 24-hr alias, and your longitude holds the key. joe