{
  "bibcode": "2008GCN..7552....1K",
  "body": "N.P.M. Kuin (MSSL/UCL) and J.Mao (INAF) report on behalf of the\nSwift-UVOT team:\n\nThe Swift/UVOT started observations of  GRB 080330 (Mao et al,\nGCN Circ. 7537) with a settling exposure in the UVOT v-filter\nstarting 2008-03-30 at 03:42:19 U, 63 seconds after the BAT\ntrigger, and a finding chart exposure in the white filter starting\n83 seconds after the trigger. During the subsequent exposure in the\nV filter, starting at 189 seconds after the trigger, the spacecraft\nlost lock and drifted. In the V image, a clear trail is visible\nthat all the stars in the field follow. In other filters, there is\nno clear evidence of lost counts, except in one image in b. Those\nexposures are short, or have much background (white), which suggest\nthat only a fraction of the counts is lost.\n\nThe extraction of the magnitudes below relies on a 5� aperture\naround the source. No counts are visible due to the source outside\nthe aperture in the images. However, these magnitudes should be\nregarded as upper limits until a more detailed reduction can be\ndone. Based on some tests, the magnitude may be underestimated as\nmuch as 0.7 magnitudes. The v-filter data were extracted using\nan aperture closely matching the shape of the trail and were\nmeasured from the event data. There is an uncertainty in this\napproach as well, since it is not clear what part of the PSF is\nsampled. Therefore the V magnitudes can be over-or underestimated\nby 0.25 magnitudes.\n\nThe observations start before a peak is reached. In the white filter,\na peak is apparent at T+128 +/- 5 seconds. In the v filter data, two\npeaks may be present at T+ 438 and 1038 +/- 25s. It is unlikely that\nthe satellite drift caused these variations because the aperture\nincluded the whole trail. The uvw1 magnitude has upper limits until quite\nlate in the burst, and must rise between T+791 and T+1416s. This\nis an indication of achromatic evolution in this burst.\n\nOnly an upper limit is found in the uvw2 and uvm2 filters,\nwhich is consistent with the reported redshift of 1.51 (Malesani,\net al. GCN 7544, and Cucchiara et al. GCN 7547).\n\nFilter Tstart(s) Tstop(s) Exp(s) Mag     Mag-error [systematic error]\n\nwh         83     183      98    18.2       0.06 [+0.7]\nv         189     588     399.8  18.5-17.2  0.3  [+/-0.25] (*)\nuvm2      594    1390      58.4 >18.55           (3 sigma UL)\nuvw1      619     638      19.5 >18.02           (3 sigma UL)\nu         644     664      19.4  17.14      0.16 [+0.7]\nb         669     678       9.6  18.9       0.6  [+0.7]\nwh        683     693       9.8  17.76      0.14 [+0.7]\nuvw2      698     870      38.9 >18.77           (3 sigma UL)\nuvw1      772     791      19.8 >18.04           (3 sigma UL)\nu         796     815      19.4  16.66      0.17 [+0.7]\nb         822     832       9.6  17.66      0.22 [+0.7]\nwhite     836     979     107.8  17.55      0.03 [+0.7]\nv         985    1384     400    18.0-17.2  0.3  [+/-0.25] (*)\nuvw1     1416    1436      19.4  17.7       0.3  [+0.7]\nb        1464    1483      19.8  18.14      0.22 [+0.7]\nwhite    1490    1499       9.6  17.91      0.15 [+0.7]\n\n(*) For the V magnitudes the range is given as seen in the event data.\n\nThe values quoted above are not corrected for the expected Galactic\nextinction corresponding to a reddening of E_{B-V} = 0.02 mag in the\ndirection of the burst (Schlegel et al. 1998).",
  "circularId": 7552,
  "createdOn": 1206919721000,
  "email": "npkuin@googlemail.com",
  "subject": "GRB 080330 Swift-UVOT refined analysis",
  "submitter": "Paul Kuin at MSSL  <npkuin@googlemail.com>",
  "eventId": "GRB 080330"
}