From jop at astro.columbia.edu Wed Aug 4 14:18:58 2021 From: jop at astro.columbia.edu (Joe Patterson) Date: Wed, 4 Aug 2021 14:18:58 -0400 Subject: (cba:news) V1674 Her: nova of the century Message-ID: <29a6c75d-33d9-42b3-e13d-7965402e2f15@astro.columbia.edu> Hi CBAers, Novae of the century were plentiful in tThe 20th century. There was GK Per in 1901, V603 Aql in 1918, DQ Her in 1934, V1500 Cyg in 1975, and V1974 Cyg in 1992. At least Starrfield and Shore, who so named the 1992 nova (see Sky and Telescope article), had the patience to wait until late in the century to award that designation. But all five stars continue to reward faithful study and shed new light on these stellar explosions. That's remarkable; most novae fade from headlines as soon as the next one appears - and fade from research papers nearly as fast.. The 21st century has seen no stunning new nova discovery. Maybe that's because they're more plentiful; with fancier and more sensitive toys, astronomers may get distracted by the next nova, and never get around to close study of last month's surprise. (Except for Ulisse Munari; *nothing* distracts him.) But this year's applicant for century royalty - v1674 Herculis - has great credentials. Still 7 mag above quiescence, when the big luminous shell still dominates, it is displaying periodic signals at 8 minutes and 3.2 hours. We've never seen this before in a still-bright nova (and neither has anyone else). Has anyone been looking properly? Well, maybe... and maybe not. But let's not repeat past negligence. It's a good season for Hercules; and with a dec of +14, could be a good target for Aussies/Kiwis/Asians as well. We'd sure love to go around the world on this guy! Length of run is a big issue. With a V filter, differential extinction is small, and you could perhaps stretch it to 2.5 airmasses. But then you lose signal-to-noise (14.5 mag now and fading). Otherwise,enforce a limit of 2.0 airmasses... and we'll rely on longitude spread to get the period structure precisely right. (Fainter than 16, this is by far the better strategy.) joe ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists https://cbastro.org/communications/mailing-lists/ From jop at astro.columbia.edu Fri Aug 6 08:37:50 2021 From: jop at astro.columbia.edu (Joe Patterson) Date: Fri, 6 Aug 2021 08:37:50 -0400 Subject: (cba:news) V1674 Her, again Message-ID: <92151cc3-50b4-9fbf-e7a0-005369450b99@astro.columbia.edu> Hi CBAers, A couple of extra remarks on the (reasonably) new nova. 1. Try for long runs. As usual, we try to splice runs from distant longitudes to establish a consistent magnitude scale. (The fact that it's not a *standard* magnitude scale is not important or relevant.) Lately, that magnitude scale is Tonny Vanmunster's, since his runs from Spain have been the most abundant. So efforts to observe when Hercules is still reasonably available in the sky of western Europe would be nice. Probably we'll also have a well-established scale in the USA before long, once the western observers jump in. 2. I notice from data submissions that these magnitude offsets are changing significantly. That is very likely because people are changing comparison stars or filters, probably in response to the nova's rapid fading. Some indication of this in the submission (the data file, or the accompanying letter) would be helpful. My guess is you'll probably want to stick to unfiltered from here on, unless the nova unexpectedly brightens (a lot). 3. The pattern of variability is still not clear, but is something I've never seen before in a nova. And I've been looking a LONG time! joe ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists https://cbastro.org/communications/mailing-lists/ From jop at astro.columbia.edu Fri Aug 13 06:03:28 2021 From: jop at astro.columbia.edu (Joe Patterson) Date: Fri, 13 Aug 2021 06:03:28 -0400 Subject: (cba:news) Periods in freshly erupted novae In-Reply-To: References: Message-ID: <46b24a2e-4152-1ce8-0d41-7eb87ff57a94@astro.columbia.edu> For those of you not subscribing to ATEL, here's the notice we just put out, based on the CBA data so far. The star is now magnitude 15.2, and still of very high importance. It's strange to see these signals - quite common signatures of CVs in their normal states - showing up in so bright a star, with very bright and presumably large unpulsed light sources (a still-young nova!) still present to dilute the pulsed fraction. This will mutate into a (much) more complete ApJ submission by October 1, with all the CBA contributors as named co-authors. If we are to understand this, we need to do a much better job studying the light curves of freshly-erupted novae. "Freshly" meaning from ~20 days to ~20 years. I'll send out some suggestions in a few days. For starters, consider these: V1974 Cyg, V1500 Cyg, V1494 Aql, QU Vul, V Per. A motley crew, but likely very interesting if you can go that faint. joe ------------------------------------------------------------------------------ The Astronomer's Telegram http://www.astronomerstelegram.org ============================================================================== ATEL #14856 ATEL #14856 Title: The Orbital and Pulse Periods of V1674 Herculis Author: J. Patterson (Columbia Univ.), M. Epstein-Martin (Columbia Univ.), T. Vanmunster (CBA-Belgium), J. Kemp (Middlebury Coll.), on behalf of the Center for Backyard Astrophysics collaboration Queries: jop at astro.columbia.edu Posted: 12 Aug 2021; 22:24 UT Subjects:Optical, Binary, Cataclysmic Variable, Nova, Transient We have carried out time-series photometry of V1674 Herculis = Nova Her 2021 with the globally distributed telescopes of the Center for Backyard Astrophysics. During 2021 July 1 - August 10, the star displayed a strong double-humped photometric signal at 0.15302(2) days, and another strong signal at 8.3586(3) minutes. The latter seems consistent with the 8.357 min signal detected in pre-outburst ZTF data by Mroz et al. (ATel #14720), and the 8.4 min X-ray signal reported in outburst by Maccarone et al. (ATel #14776). Writing our two strong signals as Omega and omega, we find weaker but clear detections at omega-Omega and omega-2Omega. This is all standard fare for an intermediate polar (DQ Her star), although there is no precedent for such signals in so bright a star (M_V~0), and so far above quiescence (7 mag). The mean orbital light curve of V1674 Her during 2021 July 1 - August 10 is shown at https://cbastro.org/the-astronomers-telegram/2021-august/ . The amplitude grew significantly during this interval, when the V-band brightness faded by 2 magnitudes. Center for Backyard Astrophysics: https://cbastro.org/ ------------------------------------------------------------------------------ Password Certification: Joseph Patterson (jop at astro.columbia.edu) https://www.astronomerstelegram.org/?read=14856 ============================================================================== ============================================================================== This is an automatically-generated notice. ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists https://cbastro.org/communications/mailing-lists/ From jop at astro.columbia.edu Thu Aug 19 04:41:46 2021 From: jop at astro.columbia.edu (Joe Patterson) Date: Thu, 19 Aug 2021 04:41:46 -0400 Subject: (cba:news) splicing CV light curves Message-ID: <9957a231-c8bb-745e-6286-8d48d676aa46@astro.columbia.edu> Hi CBAers, This is more along the lines of "chat"... but I see a particular night that illustrates the difficulties and successes of splicing data for multi-longitude light curves. With filtered data, clear nights, and many well-placed longitudes, this is totally straightforward. But such conditions never apply in the real world. 1. We're almost always stuck with unfiltered or wide-bandpass data, because our targets are just too faint for anything else. This introduces differential extinction, which is why we avoid airmasses greater than 2.0. 2. Longitudes. In the north, Europe-USA is sometimes easily spliced (long winter nights), and sometimes not (summer). Quebec (Damien) and Chile (Josch) often help in the splice. The south is more challenging, with wider oceans and fewer observers. 3. Since we are mainly period-mongerers, failing in the splice is usually no big deal. It basically means that we're somewhat blind to small periodic signals in the range 0.5-2.0 days. No problem outside that range, and not for large signals either. Only in RARE cases do we miss the interesting physics we could learn from full-time, well-calibrated coverage (like a satellite - although they too have problems). 4. A recent night illustrates these matters. I attach data on V1674 Her from three observers: Tonny (Spain), Damien (Quebec), and Joe U (Illinois). If you plot them up with separate colors, you'll see that Tonny and Joe have only a small magnitude offset, and Damien's magnitudes are systematically ~0.06 mag fainter. I go through this ritual for essentially every night and every star, applying additive offsets to get a consistent scale. (Although for the fast periods which are our most common target, it doesn't really matter - I just "zero" every file.) 5. For V1674 Her, the 501-sec and 3.666 hr signals are obvious and seemingly dominant. But there are small *slopes* in the nightly magnitudes that make me suspect some longer-period signal. So some extra effort to obtain longer light curves might be nice - especially the Western USA (if you can see though the smoke!). Finally, Hercules season is nearing an end, but Cygnus season is perfect (and long). V1500 Cyg will be a great target throughout the next three months. It's scarily faint (18.5-19), but the signals are very strong and slow (3-hour-ish). Give it a try! joe p -------------- next part -------------- 443.36791 15.580 443.36869 15.621 443.36949 15.594 443.37029 15.636 443.37112 15.603 443.37221 15.592 443.37307 15.579 443.37385 15.607 443.37464 15.603 443.37544 15.600 443.37628 15.649 443.37708 15.652 443.37786 15.654 443.37866 15.651 443.37944 15.658 443.38029 15.615 443.38108 15.673 443.38186 15.644 443.38265 15.645 443.38346 15.571 443.38435 15.605 443.38515 15.614 443.38594 15.617 443.38672 15.608 443.38752 15.628 443.38838 15.616 443.38918 15.661 443.38997 15.599 443.39076 15.642 443.39156 15.624 443.39241 15.673 443.39321 15.640 443.39399 15.651 443.39478 15.620 443.39557 15.575 443.39647 15.595 443.39727 15.614 443.39807 15.565 443.39885 15.596 443.39965 15.652 443.40050 15.611 443.40130 15.630 443.40209 15.648 443.40622 15.584 443.40706 15.622 443.40786 15.635 443.40865 15.587 443.40943 15.598 443.41219 15.592 443.41311 15.631 443.41390 15.610 443.41550 15.629 443.41628 15.623 443.41713 15.715 443.41792 15.650 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https://cbastro.org/communications/mailing-lists/ From jop at astro.columbia.edu Sat Aug 28 12:25:08 2021 From: jop at astro.columbia.edu (Joe Patterson) Date: Sat, 28 Aug 2021 12:25:08 -0400 Subject: (cba:news) Novae for September-October Message-ID: <6f849edc-1dd9-7e33-c7fa-b5733cee0fa8@astro.columbia.edu> Hi CBAers Terrific coverage of N Her 2021 = V1674 Her coming in. The star continues to taunt us with its strong orbital and pulse signals - even though it's still 4-5 magnitudes above quiescence. Pretty clear evidence of greatly enhanced mass accretion. Let's keep it rolling until evening twilight puts us out of business in late September. The other seasonally appropriate novae are: V1500 Cyg, V4743 Sgr, V1494 Aql, and V1974 Cyg. In the early morning sky, try V Per. All somewhat challenging, esp. the first two. Less daunting targets are V Sge, and the intermediate polars (Enrique keeps up with them better than I do, and will probably have good advice). But I'm inclined to suggest V418 Gem and V2306 Cyg. (And DQ Her, but only if you can afford a time resolution 20 s or less). Koji Mukai, bless his heart, has updated his list of recent classical novae: https://asd.gsfc.nasa.gov/Koji.Mukai/novae/novae.html It's a great list to study for stars which are (OK, were) bright and seasonally appropriate. To me the most interesting seem to be V392 Per, NR TrA, V407 Lup, and HV Cet. None really well-placed, but worth waiting for. But most of all, keep up the pressure on V1674 Her! joe p ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists https://cbastro.org/communications/mailing-lists/