0ptical observations of GRB afterglows: GRB 970508 and GRB 980326 revisited

Since January 1997, we have monitored 15 GRB fields, detecting 6 optical/IR afterglows. For GRB 970508, we derive a power-law decay exponent alpha = -1.19 (R-band). The luminosity of the host galaxy L relative to the characteristic luminosity L^{star} is in the range 0.06--0.15, i.e. a dwarf galaxy. For GRB 980326, we derive a power-law decay exponent alpha = -1.7, taking into account the new upper limit for the host as R > 27.3 provided by Bloom and Kulkarni (1998). This implies one of the fastest GRB optical decays ever measured. The fact that only about 50% of optical transients have been found within the gamma/X-ray error boxes, suggest that either considerable intrinsic absorption is present or that some optical transients display a very fast decline. We also propose that the secondary maximum detected on 17 Apr 1998 could be explained in the context of the SN-like light curves 2-3 weeks after the GRB, as recently suggested by Woosley (1999).Comment: Accepted for publication in Astronomy and Astrophysics Supplement Series (special issue on "Gamma-ray bursts in the afterglow era"). 2 pages and 2 postscript figure

Follow-up observations from observatories based in Spain

We present a review of the follow-up observations carried out from observatories located in Spain; Calar-Alto, Izanha and Roque de Los Muchachos. It summarizes the observations carried out by our group for 27 GRBs occurred in the period 1999-2000, spanning from GRB 990123 to GRB 001007.Comment: 3 pages, no figures. To appear in the proceedings of the October 2000 Rome Workshop on ``Gamma-Ray Bursts in the Afterglow Era'

Design, Manufacturing, and Commissioning of BIRCAM (Bootes InfraRed CAMera)

This paper covers the various aspect of design, manufacturing and commissioning of the infrared camera BIRCAM, installed at BOOTES-IR, the 60 cm robotic infrared telescope at Sierra Nevada Observatory (OSN, Granada, Spain). We describe how we achieved a quality astronomical image, moving from the scientific requirements

Four Years of Realtime GRB Followup by BOOTES-1B (2005-2008)

Four years of BOOTES-1B GRB follow-up history are summarised for the first time in the form of a table. The successfully followed events are described case by case. Further, the data are used to show the GRB trigger rate in Spain on a per-year basis, resulting in an estimate of 18 triggers and about 51 h of telescope time per year for real time triggers. These numbers grow to about 22 triggers and 77 h per year if we include also the GRBs observable within 2 hours after the trigger.Comment: 16 pages, Accepted into Proceedings of AstroRob Malaga 200

Design, Manufacturing, and Commissioning of BIRCAM (Bootes InfraRed CAMera)

This paper covers the various aspect of design, manufacturing and commissioning of the infrared camera BIRCAM, installed at BOOTES-IR, the 60 cm robotic infrared telescope at Sierra Nevada Observatory (OSN, Granada, Spain). We describe how we achieved a quality astronomical image, moving from the scientific requirements

Recent GRBs observed with the 1.23m CAHA telescope and the status of its upgrade

We report on optical observations of Gamma-Ray Bursts (GRBs) followed up by our collaboration with the 1.23m telescope located at the Calar Alto observatory. The 1.23m telescope is an old facility, currently undergoing upgrades to enable fully autonomous response to GRB alerts. We discuss the current status of the control system upgrade of the 1.23m telescope. The upgrade is being done by the ARAE our group, based on members of IAA (Instituto de Astrofiisica de Andalucia). Currently the ARAE group is responsible to develop the BOOTES network of robotic telescopes based on the Remote Telescope System, 2nd Version (RTS2), which controls the available instruments and interacts with the EPICS database of Calar Alto. Currently the telescope can run fully autonomously or under observer supervision using RTS2. The fast reaction response mode for GRB reaction (typically with response times below 3 minutes from the GRB onset) still needs some development and testing. The telescope is usually operated in legacy interactive mode, with periods of supervised autonomous runs under RTS2. We show the preliminary results of several GRBs followed up with observer intervention during the testing phase of the 1.23m control software upgrade.Comment: 15 pages, 7 figures. Accepted for publication in the Special issue "Robotic Astronomy" of Advances in Astronomy. It includes two iterations with the referee

OCTOCAM: A fast multichannel imager and spectrograph for the 10.4m GTC

OCTOCAM is a multi-channel imager and spectrograph that has been proposed for the 10.4m GTC telescope. It will use dichroics to split the incoming light to produce simultaneous observations in 8 different bands, ranging from the ultraviolet to the near-infrared. The imaging mode will have a field of view of 2' x 2' in u, g, r, i, z, J, H and Ks bands, whereas the long-slit spectroscopic mode will cover the complete range from 4,000 to 23,000 {\AA} with a resolution of 700 - 1,700 (depending on the arm and slit width). An additional mode, using an image slicer, will deliver a spectral resolution of over 3,000. As a further feature, it will use state of the art detectors to reach high readout speeds of the order of tens of milliseconds. In this way, OCTOCAM will be occupying a region of the time resolution - spectral resolution - spectral coverage diagram that is not covered by a single instrument in any other observatory, with an exceptional sensitivity.Comment: 11 pages, 10 figures, SPIE 2010 Astronomical Instrumentatio

Infrared and Optical Observations of GRB 030115 and its Extremely Red Host Galaxy: Implications for Dark Bursts

We present near-infrared (nIR) and optical observations of the afterglow of GRB 030115. Discovered in an infrared search at Kitt Peak 5 hours after the burst trigger, this afterglow is amongst the faintest observed in the R-band at an early epoch, and exhibits very red colors, with $R-K\approx 6$. The magnitude of the optical afterglow of GRB 030115 is fainter than many upper limits for other bursts, suggesting that without early nIR observations it would have been classified as a ``dark'' burst. Both the color and optical magnitude of the afterglow are likely due to dust extinction and indicate that at least some optical afterglows are very faint due to dust along the line of sight. Multicolor {\it Hubble Space Telescope} observations were also taken of the host galaxy and the surrounding field. Photometric redshifts imply that the host, and a substantial number of faint galaxies in the field are at $z \sim 2.5$. The overdensity of galaxies is sufficiently great that GRB 030115 may have occurred in a rich high-redshift cluster. The host galaxy shows extremely red colors (R-K=5) and is the first GRB host to be classified as an Extremely Red Object (ERO). Some of the galaxies surrounding the host also show very red colors, while the majority of the cluster are much bluer, indicating ongoing unobscured star formation. As it is thought that much of high redshift star formation occurs in highly obscured environments it may be that GRB 030115 represent a transition object, between the relatively unobscured afterglows seen to date and a population which are very heavily extinguished, even in the nIR.Comment: 19 Pages. ApJ 2006, 647, 47