GRB 990705 - NTT observations

GRB 990705

Images taken at La Silla with NTT (H filter)

1999 July 5-6: NTT + SofI + H filter

before the cure
after the cure

The infrared H-band counterpart of GRB990705 (marked with the green arrow) is clearly seen in the 1999 July 5.94 summed 20-min. image (top), while is almost under the detection threshold in the 1999 July 6.95 summed 10-min. image (bottom). North is to left, East is at bottom (rotated rightwards of 13 degrees); the field size is about 2'.5 x 2'.5.


GCN Circular no. 377


Infrared and Optical Observations of GRB990705

E. Palazzi, N. Masetti, E. Pian, F. Frontera, L. Amati (ITESRE-CNR, Bologna), M. Mendez, P. Vreeswijk, E. Rol, T. Galama, F. van der Hooft, M. van der Klis, M. Heemskerk, (Univ. of Amsterdam), J. van Paradijs (U. of Amsterdam and U. of Alabama in Huntsville), L. Hunt (Astr. Obs. of Arcetri), L.A. Antonelli, G. Marconi (Astr. Obs. of Rome), E. Kuulkers (SRON, Utrecht), T. Augusteijn, H. Boehnhardt, C. Lidman, L. Vanzi (ESO), M. Feroci (IAS-CNR, Rome), and C. Kouveliotou (MSFC/NASA) report on behalf of a large collaboration:


"We have observed the error box of GRB990705 (BeppoSAX mail # 99/16 and 99/17) at the ESO NTT with SOFI in H filter for 20 minutes starting on July 5.94 UT and for 10 minutes starting on July 6.95 UT. An object of H = 16.7 +- 0.1 is detected in the first night at RA = 05 09 55.4, Dec = -72 08 01 (astrometric uncertainty of 1".5), and not in the second night, with a 3-sigma upper limit of H >~ 19. The position of the transient is consistent with that of the X-ray transient detected with the SAX NFIs (Gandolfi, GCN 373).
We propose that the transient source is the infrared counterpart to GRB 990705. Assuming a power-law temporal fading, the measured magnitude and upper limit would imply that the decay index is < -1.4.

In a 10-minutes exposure taken at the VLT with FORS1 in the V filter on July 6.40 UT in very bad seeing conditions (~2".5) the source is detected at 3-sigma confidence level with V ~22.5, linked to the standard sequence PG 2331+055 (Landolt 1992, AJ 104, 340).

A 7.5-min exposure with the ESO 2.2m telescope at La Silla on July 6.44 UT yields no detection, to a 3-sigma limiting magnitude of B ~22, linked to the USNO-A1.0 star at RA = 05 09 42.59, Dec = -72 07 41.2 (J2000) which has B = 19.1."

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GCN Circular no. 382


Updated Astrometry for the IR Counterpart of GRB990705

E. Palazzi, N. Masetti, and E. Pian (ITESRE-CNR, Bologna) report:


"We have carefully checked the astrometry of the NTT+SOFI image taken on July 5.94 UT (Palazzi et al. GCN # 377), and have found that the correct coordinates of the IR transient are

RA (2000) = 05 09 54.5,
Dec (2000) = -72 07 53

The astrometric uncertainty is 0".5.

The NTT+SOFI images relative to the IR transient detection (GCN # 377) can be viewed at

http://tonno.tesre.bo.cnr.it/~masetti/grb990705.html"


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