Alert Notice 403: Request for observations of V2105 Oph in support of HST observations

August 30, 2009


Dr. Brian Espey (Trinity College, Dublin, Ireland) has requested photoelectric photometry and bright star CCD photometry of the semiregular variable V2105 Oph beginning immediately.  These observations are in support of ultraviolet spectroscopy to be obtained with the Hubble Space Telescope on Wednesday, September 2, 2009.  Observations are requested to continue through Sunday, September 6, 2009.

Photoelectric observers are asked to obtain nightly V-band photometry of V2105 Oph using the following comparison and check stars:

Comparison:     SAO 141187 (AUID 000-BBX-527, "3 Oph")
                RA/Dec(J2000): 16:27:48.18 , -08:22:18.2
                V=4.632, (B-V)=0.174 (Mermilliod and Mermilliod 1998)

Check:          SAO 141066 (AUID 000-BBX-218, "18 Sco")
                RA/Dec(J2000): 16:15:37.33 , -08:22:11.9
                V=5.505, (B-V)=0.648 (Mermilliod and Mermilliod 1998)
                (Note: this is an "NSV" star, but is microvariable only)

This star has been added to the PEPObs system in WebObs; observations may be submitted as with all other PEP program stars.

For CCD and DSLR observers, please obtain multiple exposures and coadd frames to obtain good signal to noise on nearby faint stars.  There are at least four potential comparisons within 30 arcminutes brighter than V=10.2:

  Star                   RA             Dec          V     B-V      Sp      Distance (")
BD -07 4291  16:27:42.5  -07:54:0.53  9.7    ?        K?           1073
BD -07 4293  16:27:46.2  -07:54:05.7 10.2  +1.2   mid-K       1094
HD   148179  16:26:35.2  -07:51:05.2  8.56 +0.51  G dwarf?  1365
BD -07 4289  16:27:39.4  -07:59:53.0  9.3?   ?       A?            1442

V2105 Oph is located at the following (J2000) coordinates:

        RA,Dec: 16:27:43.46 , -07:35:51.2

Finder charts for V2105 Oph may be plotted using VSP:

Please submit all observations as "V2105 OPH". 

This AAVSO Alert Notice was prepared by M. Templeton.



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