Call for observations of V348 Pup (= 1H0709-36)

(from vsnet-alert 311)

Dear CV-observers,

The eclipsing cataclysmic variable V348 Pup (= 1H0709-36) will be the subject of an HST cycle 6 program, aiming to perform multiwavelength eclipse mapping. A good/reliable ephemeris of eclipse minimum is crucial in order to properly center the eclipses in the narrow HST observing windows (some 40-mins). My last observations of this target, back in 1992, indicate that the former ephemeris was in error by some 30-mins at that time (and certainly more by now!).

I would appreciate to have your help in trying to obtain a revised ephemeris for this target (it is hardly observable from the northern hemisphere). The coordinates of V348 Pup are (J2000),

RA: 07 12 32.9 DEC: -36 05 40.4

A good finding chart can be found in the Catalog and Atlas of CVs by Downes and Shara (1993, PASP 105, 127). V348 Pup has magnitude V~15 outside of eclipse but goes down to V~17 at mid-eclipse time. The target is well positioned in the (southern) sky at this epoch of the year, so observations could be done at pretty any time during a night (by a properly positioned observer). Some 3-5 eclipse timings would be enough to derive an updated ephemeris by joining them with the previously published ones.

Due to error propagation, my estimate is that the actual eclipses are happening some 50-mins *before* the times predicted by the ephemeris of Tuohy et al. (1990). The following provisional ephemeris may be used to estimate times of mid-eclipse,

Tmid= HJD 2447210.12091 + 0.1018389075 E.

If you are able or intend to obtain some observations for this purpose please let me know. Of course, those who obtain useful ground-based data will be included as co-authors in the appropriate papers on the HST observations.

My best regards,

Raymundo Baptista

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