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Special Notice #299: Observations needed TODAY of SDSS J164248.52+134751.4

October 10, 2012: Dr. Boris Gaensicke (leader of the consortium observing CVs with the HST COS instrument; see AAVSO Alert Notice 471 and AAVSO Special Notice #297 for details and instructions) writes with an urgent message:
"STScI would like an update on SDSS J164248.52+134751.4 by ~16UT TODAY (2012 October 10), when the star is not easily visible for most of our observers. Any observations from Europe early this evening will be most welcome."

HST is scheduled to observe this CV on October 12 and the team, which has to make a go/no-go decision later today, is anxious that it might not be at minimum, as it has small brightenings from 18th magnitude.

If it is at all possible, please observe SDSS J164248.52+134751.4 and report your observations to the AAVSO International Database at once, using the name SDSS J164248.52+134751.4. Use this name to generate charts with the AAVSO Variable Star Plotter (

Coordinates:  R.A. 16 42 48.51     Dec. +13 47 51.5  (2000.0)

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


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