(cba:news) V713 Cep outburst; also VZ Scl, IM Eri (no go)

Joe Patterson jop at astro.columbia.edu
Mon Nov 13 06:10:18 EST 2017

V713 Cep richly deserves observation.  If in superoutburst, it's a GREAT 
target.  If in normal outburst, it's an excellent target.  And even if 
in quiescence, it's not too shabby either.

With our recent successes* re WZ Sge and ES Cet, I've come to realize 
that we are in a great position to make some impactful studies of 
orbital-period changes.  For years I didn't think so, because with our 
small scopes, our signal-to-noise is poor near the bottoms of typical 
deep eclipses (typically mag 17-20), or typical shallow eclipses (just 
0.2 mag deep).  Now I realize: WRONG on both counts.  Even with 
40-second integrations, it's easy for us to get an accuracy ~5 seconds - 
because integrative sampling is equivalent to instantaneous sampling, 
and because we commonly get very large amounts of data (say 40 eclipses 
per season).

Plus we're there year after year.  Some of the present campaigns are in 
part motivated by orbital-period issues (BT Mon**, X Cha, OY Car, U Gem).

Two stars to discontinue coverage: VZ Scl (excellent season, but we're 
done) and IM Eri (analysis of last year's data suggests this star is 
really complicated!).


*Success here meaning completion of a paper reporting a many-year 
campaign and its consequences.  We have some smaller successes along the 
way, of course.

**BT Mon is special, because its Porb = 0.3338 days.  Thus its eclipses 
drift by only 2 minutes per day.  So space out your observations of this 
guy.  We want the full orbital light curve, not just the (very deep!) 
eclipse.  But it's NOT a star for the usual CBA style ("hit it every 
night, in as dense a cluster as weather permits").


Beautiful planetary conjunction in tonight's morning sky!

-------- Forwarded Message --------
Subject: [vsnet-outburst 21482] V713 Cep outburst
Date: Mon, 13 Nov 2017 10:17:14 +0900
From: Taichi Kato <tkato at kusastro.kyoto-u.ac.jp>
To: suuma at yahoogroups.com, variable_star_forum at yahoogroups.com, 
vsnet-alert at ooruri.kusastro.kyoto-u.ac.jp, vsnet-alert at yahoogroups.com, 
vsnet-campaign-dn at ooruri.kusastro.kyoto-u.ac.jp, 
vsnet-outburst at ooruri.kusastro.kyoto-u.ac.jp, vsnet-outburst at yahoogroups.com

V713 Cep outburst

    Eclipsing dwarf nova below the period gap.  No superoutburst
has been observed.

   YYYYMMDD(UT)   mag  observer
   20171030.521  <163c  (Mitsutaka Hiraga)
   20171108.516  <163c  (Mitsutaka Hiraga)
   20171112.794  158C  (Jeremy Shears)

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