ATOM

Automatic
Telescope for
Optical
Monitoring
for H.E.S.S.

Project description

This activity is one part of the participation of the LSW at the H.E.S.S.-project. See this page for a detailed description of our activities concerning H.E.S.S..

ATOM (Automatic Telescope for Optical Monitoring) is a 75cm telescope currently being upgraded to work in a fully robotic way, i.e. do its complete work without human attendance. ATOM is part of the H.E.S.S.-project and will serve as:

an automatic optical monitor of variable gamma-ray sources
an automatic optical monitor of potential H.E.S.S. targets
a transmission monitor to help calibrate the Cherenkov shower image analysis

The automatisation of the telescope was done as a collaboration between Landessternwarte Heidelberg-Königstuhl and Hamburger Sternwarte.

Publications

The following publications are containing data provided by ATOM:

refereed journals

The first gamma-ray outburst of a narrow-line Seyfert 1 galaxy: the case of PMN J0948+0022 in 2010 July Monthly Notices of the Royal Astronomical Society, 413: 1671–1677
Discovery of VHE gamma-rays from the BL Lacertae object PKS 0548-322, 2010A&A...521A..69A
Multi-wavelength observations of H 2356-309, 2010A&A...516A..56H
Multiwavelength Monitoring of the Enigmatic Narrow-Line Seyfert 1 PMN J0948+0022 in 2009 March-July, 2009ApJ...707..727A
Fermi/Large Area Telescope Discovery of Gamma-Ray Emission from the Flat-Spectrum Radio Quasar PKS 1454-354, , 2009ApJ...697..934A
Simultaneous observations of PKS 2155-304 with HESS, FERMI, RXTE, and ATOM: Spectral energy distributions and variability in a low state, 2009ApJ...696L.150A
Discovery of VHE gamma-rays from the high-frequency-peaked BL Lacertae object RGB J0152+017, 2008A&A...481L.103A
New constraints on the mid-IR EBL from the HESS discovery of VHE gamma-rays from 1ES 0229+200, 2007A&A...475L...9A
Discovery of VHE gamma-rays from the distant BL Lacertae 1ES 0347-121, 2007A&A...473L..25A

conference proceedings

The 2010, February 19 stellar occultation by Varuna, 2010DPS....42.2311S
Broadband Multi-wavelength Campaign On PKS 2005-489 in a High State, 2010HEAD...11.3325K
Broadband multi-wavelength campaign on PKS 2005-489, 2009arXiv0912.3741K
Correlation between the synchrotron and the inverse-Compton components, in the longterm light curve of GeV blazars, 2009arXiv0908.4577B
Atmospheric extinction monitoring using multi-color starlight, 2008AIPC.1085..696H
Multiwavelength analysis of the TeV Blazar RGB J0152+017, 2008AIPC.1085..549K
Discovery and Multi-wavelength Study of a BL Lac RGB J0152+017, 2008cosp...37.2192N

Astronomers Telegrams

Detection of an optical flare from blazar PKS 1424-41, 2010ATel.2613....1H
Detection of an optical flare from PKS 1222+216 (4C 21.35), , 2010ATel.2436....1H
Detection of an optical flare from PKS 2052-474, 2009ATel.2158....1H
Detection of an optical flare from 3EG J1429-4217, , 2009ATel.2103....1H

Telescope

The telescope for this project is a 75-cm AltAz Telescope of the Landessternwarte Heidelberg-Königstuhl (LSW).

The telescope was build by Zeiss as a prototype for computer controlled azimuthal mounting. It was operated for a decade at LSW and used for many astronomical projects. In preparing for the start of the H.E.S.S.-project, it became apparent that multifrequency observations would best be conducted on-site, resulting in a project to robotize and relocate the telescope.
While the mechanical components did only require a modest redesign for automatic operations, the control electronics were replaced completely, following the strategies used for automatisation of the Oskar-Lühning-Teleskop (OLT, see http://www.hs.uni-hamburg.de/EN/Ins/Olt/ ). In particular, all ATOM motors are operated using industrial approved programmable logic controllers (PLCs), resulting in a very stable system.

2004 -- upgrade, new electronics
2005 -- end-to-end test, shipping to Namibia, assembly
2006 -- start of operation with scientific camera (Nov)
2007 -- upgrade to automatic system

Performance

some preliminary numbers about the telescope performance:

pointing accuracy	tracking accuracy		average seeing (rms)		limiting R magnitude (3 sigma), good/dark sky conditions, zenith angle < 30deg
pointing accuracy	w/o guiding camera	with guiding camera	B band	R band	30sec	100sec	300sec
< 20 ''	approx. 2'' / 5min	< 2 ''/ 30min	2.2 ''	2 ''	18.5	19.5	20.3

ATOM Automatic Telescope for Optical Monitoring for H.E.S.S.