Intro
We are organizing a multi-frequency monitoring of the TeV blazar Mrk421. Such campaign will start on December 8th 2009 and will last till December 2010.
The main goal of the campaign is to study the flux and spectral evolution of the broad-band emission, from radio to multi-TeV, of Mrk421.
The most important part of the campaign will be between Mid-December 2009 to Mid-June 2010; this is the time interval with good visibility for optical/TeV instruments. The goal for this time interval is to sample DAILY the peaks of the 2 bumps in the SED of Mrk421 (optical/X-ray and GeV/TeV). We have already allocated resources to do that at various energy ranges with various insrtruments (GRT,KVA,RXTE,MAGIC). I am currently trying to involve many other instruments. The current (very preliminary) observing schedule can be found here. This schedule will be updated during the following days with new instrument observations.
Swift XRT and UVOT data could be extremely useful for the proper characterization of the evolution of the SED. I submitted a Swift Cycle 6 proposal to monitor Mrk421 (see proposal here), but even it were accepted, the observations from this proposal would not start till April 2010. Therefore, we need an additional (ToO) proposal that provide us with Swift observations up to April 2010. We submitted similar ToO proposals to perform monitoring of Mrk421 (and Mrk501) for the campaigns on 2009. Those proposals were successful and provided us with very valuable data for those campaigns. The nice thing is that Mrk421 is very bright at UV/X-ray frequencies and hence a 1ks observation is already good enough to have good quality spectra and UV data points. Therefore, we can monitor this source over long time with little overall observing time.
For this proposal, we request one 1ks long observation every 2 days, starting from December 8th and finishing on April 1st. Altogether this is only 58ks which will provide very valuable information for the characterization of the evolution of the SED with time during 4 months.
Scientific Justification
The Fermi/AGN group is organizing a long multi-frequency monitoring on Mrk421,starting on December 8th 2009 and lasting 1 year. Specially critical are the energies around the peaks of the Synchrotron (~keV) and Inverse Compton (~100 GeV) bumps. Swift observations are important to provide information from energies in the range 0.2-10 keV, as well as at the UV frequencies (which are not affected by the host galaxy emission). Note that observations at UV frequencies can only be provided by Swift. Both X-rays and UV frequencies are very valuable for the correct modeling of the Synchrotron bump, and hence Swift observations will play a key role in the understanding of the physical processes occurring in this blazar.
The source is bright and hence 1 ks long observations are sufficient for significant detections with both XRT and UVOT instruments. We request Swift 1ks long observations every 2 days starting from December 8th and finishing on March 31st 2010. This is 58 ks in total. We submitted a Swift Cycle-6 proposal that (in case of being approved) could be used for the observations after March 31st. Those Swift observations will be combined with the already scheduled optical,X-ray and TeV observations, as well as with Fermi/LAT, which operates in survey mode.
The current schedule of the multi-frequency observations from this campaign can be found at the following URL: https://confluence.slac.stanford.edu/display/GLAMCOG/Campaign+on+Mrk421+%28December+2009+to+December+2010%29
The scientific return of the Swift data will be maximized if the observations are taken close in time to the (almost simultaneous) optical, RXTE and IACT observations. Yet we want to stress that these observations are requested within the constraints of the primary Swift observing program. We are aware of the very tight Swift observing schedule, and thus we only ask for a "best effort" from the Swift team.