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GRB 991216: MDM 1.3m R-band CCD Image
(J2000) 05 09 31.2, 11 17 7.2
1999 Dec. 17.142 -- 20 minute exposure
4.3 arcmin field rotated 50 deg CCW
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| GCN Circular #472: GRB 991216, Optical Afterglow |
Robert Uglesich, Nestor Mirabal, J. Halpern (Columbia U.), Susan Kassin (Ohio State), & Sebastiano Novati (College de France) report on behalf of the MDM Observatory GRB follow-up team: "We find a probable afterglow of the extremely bright BATSE burst GRB 991216 (Kippen et al. GCN #463) in a series of R-band observations taken by S. Kassin and S. Novati on the MDM 1.3m telescope. An object at (J2000) 05:09:31.2, +11:17:07.2 faded from approximately R = 18.8 on Dec. 17.142 to R = 19.4 on Dec 17.372. The corresponding power-law decay index is -1.4. This object is not visible on the digitized POSS II plate. Its position is consistent with the latest RXTE scan (Markwardt et al. GCN/RXTE_PCA notice). This preliminary photometry is based on several USNO stars. We used a nonstandard broad R filter which transforms very well with Landolt R. A finding chart is posted at http://www.astro.columbia.edu/~rru/GRB991216.html This message may be cited." |
GRB 991216: MDM 1.3-m Difference Image Discovery Frame
(J2000) 05 09 31.2, 11 17 7.2
2.1 arcmin field
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We used the image subtraction technique of Tomaney & Crotts(1996) developed for the Columbia/VATT Microlensing Survey of M31 to efficiently search the entire field of view of our images for photometrically varying sources. The optical transient was easily detected as a source 16-sigma above background. Left: 1200 second R-band exposure taken on 1999 Dec 17.142 UT with the MDM 1.3-m telescope. Right: Result of PSF-matching and subtracting a frame taken on 1999 Dec 17.372 from the image on the left. |
