Special Notice #315: HST COS observing SDSS J075507.70+143547.6 December 13-14 and HS 0218+3229 is next target

December 11, 2012:  Further to AAVSO Alert Notice 471 (www.aavso.org/aavso-alert-notice-471) and AAVSO Special Notice #309 (www.aavso.org/aavso-special-notice-309), HST COS is observing the WZ Sge-type cataclysmic variable SDSS J075507.70+143547.6 December 13-14:

            SDSS J075507.70+143547.6  13 December 2012 23:32:57 through 14 December 04:45:44 UT

PLEASE GIVE SDSS J075507.70+143547.6 TOP PRIORITY NOW - YOUR OBSERVATIONS WILL BE CRUCIAL FOR THE HST SCHEDULING TEAM TO DECIDE TOMORROW whether to carry out the observations. SDSS J075507.70+143547.6 is 18.2V at minimum and unknown at maximum.

Coordinates for SDSS J075507.70+143547.6: R.A. 07 55 07.72 Dec +14 35 47.6 (2000.0)

The next HST COS target is the UG-type dwarf nova HS 0218+3229:

                                  HS 0218+3229  22 December 2012 06:07:48 through 10:17:53 UT

Please focus on HS 0218+3229 after the SDSS J075507.70+143547.6 HST observations are over. Remember that your observations will be crucial for the HST scheduling team to decide around December 20 whether to carry out the observations. HS 0218+3229 is 15.5V at minimum and 12.5V at maximum.

Coordinates for HS 0218+3229: R.A. 02 21 33.48 Dec +32 43 23.9 (2000.0)

As instructed in AAVSO Alert Notice 471, for CCD observers, simultaneous photometry [shortly before, during, and after the HST observations] would be ideal. B filter would be best for a light curve, although for the magnitude estimates, a V measurement would be best. An uninterrupted light curve would be better than cycling between filters. SDSS J075507.70+143547.6 is most likely too faint for positive visual observations at minimum. HS 0218+3229 is a more reasonable visual target. If positive visual observations of either system are possible they are welcome, as are visual fainter-than observations fainter than magnitude 15.0.

Charts for both targets may be created using VSP (www.aavso.org/vsp).

Please report observations as soon as possible to the AAVSO International Database as SDSS J075507.70+143547.6 and HS 0218+3229, respectively. If an outburst is detected, please report observations immediately. Many thanks!

This AAVSO Special Notice was compiled by Elizabeth O. Waagen.


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