From jop at astro.columbia.edu Tue Feb 11 04:54:14 1997 From: jop at astro.columbia.edu (Joe Patterson) Date: Tue, 11 Feb 1997 04:54:14 -0500 Subject: (cba:news) the times they are a-changin Message-ID: <199702110954.EAA17140@tristram.phys.columbia.edu> Dear CBAers, 2/11/97 Whew, in two days I leave for nine weeks in South Africa. Lotta stuff to do. Wanted to get some current info in your hands. EG Cnc has grown mighty faint (17.2) and the mini-eruptions have paused for a while, but it still sports a wave in the light curve at something like the old superhump period. Dave Harvey and Bob Fried have managed to track it reasonably well in dark skies with 14- and 16-inchers. Never before have we gotten the chance to test the staying power of superhumps 5 mag below maximum light! So I earnestly implore you to try to follow this wonderful star. Only a few of you will be able to follow the short-period modulation, but snapshot magnitudes are of much interest too. We'll do spectroscopy of the star, trying to find Porb, during Feb 16-24; and will also I hope get photometric coverage from Israel during Feb 19-22. So assign it an extra high priority for the next 2 weeks (deep, deep apologies for the rampaging Moon towards the end). The other evening star these days is BH Lyn. We've been doing well on this star for 6 weeks now, with coverage from practically everyone. So I'm inclined to stay on it about four more weeks. We can't go any longer because, to be candid, once you start observing DW UMa you're likely to be hooked for the rest of its season! BH Lyn is rewarding, but DW UMa is the Mother Lode of permanent-superhump delights. So now let's talk about the UMa guy. This is definitely the best morning-sky target this month. Maybe any month. In addition to the strong negative superhumps and eclipses, the star may show something else of great interest. Plot out the light curve at the end of this letter, a long run which Tonny Vanmunster got a few days ago. In successive orbits, the star trends up, then down, then up again - as if there were a signal at about *half* the orbital frequency. I've been mystified at similar things appearing in the power spectra of other superhumpers. Only once did I really emphasize it in print (the 1995 V1159 Ori paper), but I have repeatedly seen signals at about half the main superhump frequency. Because this is a pretty low frequency and our data routinely leaves the more subtle extinction effects uncorrected, I've been unsure as to whether it's real. (Also because it really violates my intuition - I just can't understand how 2xPorb is a natural timescale in the binary!) I really wanted some bright star to come along and show the effect at large amplitude, taking it out of the realm of doubt. It seems possible that Mister DW is doing just that. So DW UMa is surely the morning-sky target of choice. Tonny's data is with a 10-inch, so there are no great demands on equipment here. He used the comp star 5 arcmin SW from the variable, designated as C1 ("primary comp") on Jonathan's official CBA charts. This star is otherwise known as GSC 3822 72, and has an official GSC magnitude of 12.5. If you might saturate on this comp, try instead Mister GSC 3822 1157 (5 arcmin WNW from the variable); it has GSC mag = 14.4 and is our "check star", labelled C2 on the CBA charts. EG, BH, and DW are the entrees through the end of February. Now SW Sex itself, the prototype of the class, is rolling into position and sits near the equator (1012-03), giving views from all over our planet. It would be great if our southern friends would start the year's coverage. Then, depending on the results, we can adjust its priority for March/April observing all over the world. I believe it will be a friendly star, with eclipses, little flickering, and a probable superhump. Again I stress that we can use snapshots too. Especially for 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. Buena suerte, I dunno how to say good luck yet in Afrikaans. joe Tonny's light curve, JD versus delta mag (V-C1): 9.6 hr and pretty nifty 486.3829 3.15 486.3838 3.35 486.3903 3.02 486.3921 2.62 486.394 2.42 486.3949 2.34 486.3958 2.23 486.3968 2.22 486.3977 2.1 486.3986 2.12 486.3995 2.02 486.4005 2.01 486.4014 1.98 486.4023 2.05 486.4033 2.07 486.4042 1.9 486.406 2.02 486.407 1.97 486.4088 1.94 486.4097 2.03 486.4107 1.95 486.4116 2.03 486.4134 1.93 486.4144 2.06 486.4153 2.05 486.419 2.07 486.4199 2.06 486.4208 2 486.4218 1.95 486.4227 1.96 486.4236 1.95 486.4245 2.03 486.4255 1.98 486.4273 1.92 486.4282 1.93 486.4301 1.82 486.431 1.81 486.4329 2.06 486.4338 1.97 486.4347 1.96 486.4356 1.96 486.4375 1.98 486.4394 1.97 486.4412 2 486.4421 2.07 486.4431 2.05 486.444 2.05 486.4449 1.98 486.4458 1.99 486.4467 2.01 486.4477 1.95 486.4486 2.02 486.4495 1.96 486.4505 1.99 486.4514 2.04 486.4523 2.04 486.4532 1.94 486.4551 1.96 486.456 1.93 486.4569 1.99 486.4579 1.98 486.4588 1.95 486.4597 1.88 486.4606 2.02 486.4625 1.93 486.4634 1.82 486.4643 1.83 486.4653 1.89 486.4662 1.85 486.468 1.77 486.469 1.74 486.4708 1.72 486.4727 1.65 486.4745 1.71 486.4755 1.65 486.4764 1.65 486.4773 1.62 486.4782 1.68 486.4791 1.65 486.4801 1.69 486.481 1.8 486.4819 1.77 486.4856 1.65 486.4866 1.69 486.4875 1.73 486.4884 1.73 486.4893 1.72 486.4921 1.64 486.493 1.59 486.494 1.55 486.4949 1.57 486.4958 1.62 486.4977 1.67 486.4994 1.64 486.5003 1.59 486.5012 1.67 486.5029 1.69 486.5038 1.68 486.5056 1.68 486.5073 1.81 486.5082 1.75 486.5091 1.75 486.5108 1.87 486.5127 1.94 486.5173 2.44 486.5182 2.68 486.5191 2.85 486.5287 2.45 486.5296 2.27 486.5306 2.12 486.5315 2.11 486.5324 2.09 486.5333 2 486.5343 2.02 486.5352 1.97 486.5361 1.94 486.537 1.93 486.538 1.89 486.5389 1.89 486.5398 1.88 486.5408 1.88 486.5417 1.87 486.5426 1.93 486.5435 1.97 486.5445 1.97 486.5454 1.94 486.5463 1.89 486.5472 1.89 486.5482 1.85 486.5491 1.89 486.55 1.92 486.5509 1.92 486.5519 1.9 486.5528 1.91 486.5537 1.89 486.5546 1.88 486.5556 1.91 486.5565 1.88 486.5574 1.87 486.5583 1.89 486.5593 1.92 486.5602 1.91 486.5611 1.9 486.562 1.85 486.563 1.86 486.5639 1.8 486.5648 1.87 486.5657 1.88 486.5667 1.92 486.5676 1.89 486.5685 1.94 486.5694 1.9 486.5704 1.9 486.5713 1.92 486.5722 1.97 486.5731 1.91 486.5741 1.9 486.575 1.94 486.5759 1.88 486.5769 1.88 486.5778 1.88 486.5787 1.91 486.5796 1.89 486.5806 1.92 486.5815 1.98 486.5824 2.04 486.5833 2.01 486.5843 1.97 486.5852 1.97 486.5861 1.94 486.587 1.97 486.588 2.01 486.5889 2 486.5898 1.99 486.5907 1.96 486.5917 1.95 486.5926 1.99 486.5935 1.93 486.5944 1.93 486.5954 1.97 486.5963 1.96 486.5972 1.93 486.5981 1.89 486.5991 1.97 486.6 1.99 486.6009 1.99 486.6018 2 486.6028 2.03 486.6037 2.02 486.6046 1.98 486.6055 1.94 486.6065 1.97 486.6074 1.93 486.6083 1.97 486.6092 1.99 486.6102 1.98 486.6111 1.97 486.612 1.97 486.613 1.94 486.6139 1.98 486.6148 2.02 486.6157 2.05 486.6167 2.03 486.6176 2.03 486.6185 2.02 486.6194 2.03 486.6203 2.1 486.6213 2.05 486.6222 2.03 486.6231 2.07 486.6241 2.07 486.625 2.09 486.6259 2.02 486.6268 2.06 486.6278 2.01 486.6287 1.99 486.6296 2.09 486.6305 2.1 486.6315 2.1 486.6324 2.05 486.6333 2.06 486.6342 2.08 486.6352 2.1 486.6361 2.09 486.637 2.07 486.6379 2.05 486.6389 1.99 486.6398 2.01 486.6407 2.09 486.6416 2.13 486.6426 2.06 486.6435 2.16 486.6444 2.16 486.6453 2.18 486.6463 2.23 486.6472 2.23 486.6481 2.28 486.6491 2.25 486.65 2.36 486.6509 2.33 486.6518 2.35 486.6527 2.44 486.6537 2.61 486.6546 2.93 486.6555 3.05 486.6564 3.3 486.6574 3.48 486.6611 3.99 486.6639 3.43 486.6648 3.24 486.6657 2.96 486.6666 2.85 486.6676 2.72 486.6685 2.6 486.6694 2.56 486.6703 2.48 486.6713 2.39 486.6722 2.35 486.6731 2.4 486.674 2.41 486.675 2.4 486.6759 2.38 486.6768 2.35 486.6777 2.38 486.6787 2.37 486.6796 2.38 486.6805 2.42 486.6814 2.52 486.6824 2.44 486.6833 2.49 486.6842 2.56 486.6851 2.55 486.6861 2.55 486.687 2.49 486.6879 2.5 486.6888 2.5 486.6898 2.25 486.6907 2.26 486.6916 2.34 486.6925 2.28 486.6935 2.28 486.6944 2.2 486.6953 2.22 486.6962 2.13 486.6972 2.19 486.6981 2.17 486.699 2.25 486.7 2.23 486.7009 2.22 486.7018 2.26 486.7027 2.19 486.7037 2.17 486.7046 2.21 486.7055 2.2 486.7064 2.32 486.7074 2.32 486.7083 2.33 486.7092 2.38 486.7101 2.38 486.7111 2.4 486.712 2.35 486.7129 2.34 486.7138 2.35 486.7148 2.33 486.7157 2.37 486.7166 2.32 486.7175 2.35 486.7185 2.29 486.7194 2.37 486.7203 2.33 486.7212 2.36 486.7222 2.28 486.7231 2.3 486.724 2.29 486.7249 2.23 486.7259 2.22 486.7268 2.22 486.7277 2.16 486.7286 2.2 486.7296 2.18 486.7305 2.24 486.7314 2.3 486.7323 2.3 486.7333 2.34 486.7342 2.3 486.7351 2.26 486.7361 2.22 486.737 2.16 486.7379 2.19 486.7388 2.12 486.7398 2.16 486.7407 2.13 486.7416 2.17 486.7425 2.15 486.7435 2.15 486.7444 2.13 486.7453 2.09 486.7462 2.16 486.7472 2.12 486.7481 2.11 486.749 2.13 486.7499 2.05 486.7509 2.07 486.7518 2.05 486.7527 2.04 486.7536 2.07 486.7546 2.04 486.7555 2.05 486.7564 1.99 486.7573 1.97 486.7583 1.96 486.7592 1.95 486.7601 2.01 486.761 1.95 486.762 2.01 486.7629 1.95 486.7638 1.99 486.7647 1.95 486.7657 1.96 486.7666 1.98 486.7675 2.05 486.7684 1.97 486.7694 1.95 486.7703 1.94 486.7712 1.97 486.7722 1.96 486.7731 2 486.774 2.03 486.7749 2.04 486.7759 2.07 486.7768 2.06 486.7777 1.95 From jop at astro.columbia.edu Fri Feb 14 14:15:38 1997 From: jop at astro.columbia.edu (Joe Patterson) Date: Fri, 14 Feb 1997 14:15:38 -0500 Subject: (cba:news) feb 19-22 Message-ID: <199702141915.OAA25017@tristram.phys.columbia.edu> Dear CBAers, Got some really fine data a few days ago on EG Cnc at mag 17.1, courtesy of Daves East and West. Fine superhump pulsing away at the usual period and phase. So that calms my last week's anxiety about this sucker! (Sorry you have to endure such things so regularly.) We decided to declare BH Lyn followed by DW UMa the objects of choice for the Wise Observatory (Israel) run during February 19-22. So these should definitely be the choice targets for everyone during, say, the 18th through the 23rd. Especially for observers at longitudes far- flung from Israel! Alon is basically going to go "1st half on BH Lyn, 2nd half on DW UMa". That would be fine, but of course very long runs are really desirable - so you could go that route instead. We will be starting spectroscopy on EG Cnc tomorrow. Star, don't erupt on us now. Leaving for South Africa in a few hours... joe