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Neglected Southern CVs

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DDE's picture
Neglected Southern CVs

This post is mostly for the Southern hemisphere observers (and, of course, for remote users of telescopes in Australia, South Africa, Chile and Argentina). I have noted recently that some rather bright cataclysmic variables discovered over the last 15 years by Calan-Tololo and Edinburgh-Cape surveys were not included in AAVSO VSX or had wrong coordinates in the database. In the last three days I have updated the positions of CTCV J0333-4451 and CTCV J2056-3014, plus made initial submissions for CTCV J1940-4724 and EC 21147-6437. Though they are not formally the part of any campaign (yet), I will try to persuade the observers (CCD or visual ones) to keep your eyes on them. One by one, constellation by constellation.

CTCV J1940-4724: - dwarf nova in Telescopium. Range 13.2-17.5m from Siding Spring Survey, orbital period 0.0809 d from single-night spectroscopic observations covering 0.11 d (less than 1.5 period)! The star is quite active, it has shown at least 14 outbursts in nine years of SSS observations. Some outbursts are to ~14m and the others to ~13m. Thus, it can be a SU UMa-type dwarf nova. Position (J2000.0): 19 40 37.6 -47 24 50

CTCV J2056-3014: - dwarf nova in Microscopium with an even brighter range 12.6-17.1m in SSS data. This one has an orbital period 0.0732 d and white dwarf spin period of 0.0107 d (15.4 min). That's why the type is UG/DQ, even though He II 4686 line is very weak in spectra. J2056-3014 was in outburst on two DSS plates out of six, and also several times in ASAS-3 data. Well worth following, too! Coordinates: 20 56 52.15 -30 14 39.1

EC 21147-6437: - eclisping CV in Pavo (Peacock) with an X-ray counterpart 1RXS J211859.0-642522. Note the Edinburgh-Cape (EC) name is in archaic B1950.0 coordinate system, so the J2000.0 position has different figures: 21 18 49.93 -64 25 13.3. This is the only eclipsing Novalike variable (NL+E) in the period gap. P is 0.111682 d (2.68 hr), the maximum magnitude varies from 14.2 to 14.6, and the minimum is 15.8m. Note the eclipses are asymmetric, so the minimum and mid-eclipse times are different. Also, if this star ever goes into an outburst, it may become brighter than VW Hya (8.4m) and SS Cyg (7.8m). Why? Because the UGSU-type variable TU Men with the closest period ( 0.1172 d) has an amplitude of 7 magnitudes (11.6-18.5 V). If EC 21147-6437 ever decides to become a dwarf nova, it will be the brightest DN on the whole sky. But who knows, it may turn into VY Scl-type anti-nova instead and go to a low state. Only observations will tell!

Good observing, and clear skies to the rest of the world while Siding Spring is clouded out until June 12th!

Denis (DDE)

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pukemaru's picture
Neglected Southern CVs

Thanks for your posting, Denis. Have you requested sequences? If not, I will.

Stephen [HSP]
New Zealand

DDE's picture
Re: Neglected Southern CVs

Hello Stephen!

I have requested AUID for J2056-3014 which didn't have one (now it has).

I also requested CCD sequence with 30'x30' area. Let's hope the Chart Team will respond soon!

Denis (DDE)

MUY's picture
Hi Denis,

Hi Denis,

Have you a list of neglected Northern CVs...?




DDE's picture
Re: neglected Northern CVs

Hi Eddy!

I don't have such a list, but here are some Northern CVs which are not in VSX and can be observed during this time of year.

SDSS J143209.78+191403.5 - faint eclipsing anti-nova (18.3-20.5) with P=0.117117 d. (Wow! Another one at the upper edge of the period gap, and the shortest period NL/VY). Eclipses to 19.6 in the "high" state (see attachment).

KIC 9202990 (18 56 08.1 +45 37 40) - dwarf nova with continuous 'stunted' outbursts. Range 14.6-15.5, period 0.170 d.

CSS J214140.4+050730 - faint eclipsing CV (18.5-19.5) with the proposed period P=0.053 in P. Szkody et al., 2014 (looks like a possible UGWZ candidate).

DDE's picture
CTCV J1940-4724 going into outburst!

CTCV J1940-4724 is rising!

  2017-06-30.683 UT  17.065CV  T32
  2017-06-30.686 UT  17.184CV  T32
  2017-07-01.607 UT  14.801CV  T32  Outburst!
  2017-07-01.610 UT  14.774CV  T32  Outburst!

Time-resolved photometry is requested. Recommended comparison star: 135 from AAVSO sequence. Check star: 152 from AAVSO sequence. Color-combined chart: (10'x10' FOV)

Important! If your FOV is larger than 15'x12' and if you can reach 17.5-18m in 60-120 sec exposure, please also report the photometry of nearby hot star SSS_J194140.2-473502 (P=0.142769 d, FUV-NUV=-0.34). See attachment for the positions of both stars marked.

Denis (DDE)

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