Special Notice #238: HST observations scheduled for GW Lib

April 2, 2011: Further to AAVSO Alert Notice 433, Dr. Paula Szkody, University of Washington, informs us that the time of the HST observations of GW Lib has been set for Friday night, 2011 April 8/9. The ground observations to confirm that the object is not in outburst - and allow the HST observations to take place - will thus need to take place on Thursday, April 7/8. However, because GW Lib is a late-night object for ground observers at this time of year, we are asking observers to make additional observations on Wednesday, April 6/7, as well.

Please continue to make one observation per night between now and April 6, and more frequent observations Wednesday, April 6/7, through Saturday, April 9/10, and then nightly observations again until the end of April.

It is extremely important that we know whether GW Lib is down as early in the evening of April 7/8 as possible, so please submit your observations from the nights of April 6/7 and 7/8 to the AAVSO as soon as you make them, using the name GW LIB.

In the event of an outburst, please contact the AAVSO immediately.

If visual observers cannot see GW Lib itself, they should report a fainter-than magnitude using the faintest comparison star visible. CCD observers are asked to use filters during observations if available; V filter is preferred, but B,Rc, and Ic may also be used. At least magnitude 15.8 needs to be reached (GW Lib is ~16.8 at minimum). Please refer to AAVSO Alert Notice 433 for additional instructions for CCD observers.

Coordinates: RA: 15 19 55.45  Dec: -25 00 25.30 (J2000.0)

Charts for GW Lib may be created using the Variable Star Plotter (VSP):

Your observations are critical to the success of these HST observations. Many thanks for your efforts and contributions!

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

Information on submitting observations to the AAVSO may be found at:


A Special Notice archive is available at the following URL:

Subscribing and Unsubscribing may be done at the following URL: