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Re: Multiwavelength Campaign for blazar 3C454.3

Hi all,
Grism observations with the SWIFT/UVOT may actually happen -- here's a little correspondence I had over the last day with Dirk Grupe and Neil Gehrles. 

Eric Perlman



Neil Gehrels wrote:

Eric,
Please feel free to forward this correspondence to the previous list of people so they become aware of the UVOT grism capabilities. 

Neil


I wrote (to Dirk Grupe):

Hi Dirk,
I actually did a calculation like this last year for XMM/OM and came up with pretty similar numbers for the observation time that would be required.
Regarding whether the interest would be in looking for flux changes or line profile changes, well, this is a completely open question. The Sikora mechanism for generating gamma-ray flares predicts that the seed photons would come from the BLR, but it's unclear whether the luminosity would reflect significant changes, or just the detailed profile. Obviously if the associated changes are small and show up only in the profile there is little chance. However that is unknown. 

Cheers,
Eric



Dirk Grupe wrote:
     Hi Neil
I had a look the the request by Eric Perlman to observe 3C 454.3 with the UV grism. Well, the redshift is 0.859, so in principle the Ly alpha and CIV lines are in the band pass of the UV grism. I have also had a look at the segment 010 photometry data and it is 13.8 mag in W1, 14.0 in M2, and 14.2 in W2, so also here a grism observation is possible. However, if we want to do this we will need more observing time. Talking with Peter Brown he suggests for a 14th mag in UV object about 4ks. So we definately have to bump up the observing time on it. Also keep in mind that the grisms only have a resolution of about R=300. So, if you are intersted in changes in the emission line fluxes, this might work, but definately not if your interest is in looking for line profile changes. Also one problem I see with the field of 3C454.3 is that there are two stars relatively close to it, so it will need a specific roll angle to avoid any overlap of the spectra. So, in short - feasible, but needs more observing time. One suggestion I have is, we could give it one shot and observe it with the UV grism for 4ks next week. One more thing to keep in mind is who will do the analysis? Sofar there is no tool for a standard analysis of the grism data. 

Hope that helps
All the best
   Dirk


Eric Perlman wrote:

Dave,
Just out of curiosity, would it be possible to also involve SWIFT to obtain monitoring of the Ly-alpha and CIV lines using the UVOT in grism mode? The idea would be to look closely at any links between BLR variability and variability at higher energies. IMHO this could be done without significantly taking away from SWIFT's primary mission of looking at GRBs and other transients. I can send more information if you're interested. 

Cheers,

Eric



Dave Thompson wrote:

Multiwavelength Colleagues,
The GLAST Large Area Telescope AGN science group is starting a multiwavelength campaign for blazar 3C454.3 (2251+158), effective immediately and continuing through the middle of August. This Ad-Hoc Intensive Campaign (AIC) is prompted by brightening in the radio, optical and X-ray. Swift Target of Opportunity observations are planned. A Spitzer observation is scheduled.
The campaign managers are: Matthias Kadler, <mailto:mkadler@milkyway.gsfc.nasa.gov>mkadler@milkyway.gsfc.nasa.gov<mailto:mkadler@milkyway.gsfc.nasa.gov> 
[]
, and Ann Wehrle, <mailto:awehrle_ssi@earthlink.net>awehrle_ssi@earthlink.net<mailto:awehrle_ssi@earthlink.net> 
[]
Please contact them if you have telescope time and are interested in joining this campaign. For this campaign, the policy on data sharing will be: if you observe and send data that can be used, you are a co-author of a resulting multiwavelength publication unless you just want an acknowledgment. Anyone who contributes data keeps the right to publish those data separately.
Information about this source and this campaign can be found at https://confluence.slac.stanford.edu/display/GLAMCOG/July%2C+2007%2C+Multiwavelength+Campaign+on+3C454.3 The data submission format and preliminary results will be available through this Web site, also.
Although there will be no GLAST gamma-ray data (GLAST is still in testing in Arizona), the opportunity for good multiwavelength coverage of this source right now is excellent at other wavelengths. In addition to the intrinsic scientific interest, this campaign can be used to establish planning and coordination routines for the upcoming years of multiwavelength blazar observations with GLAST.
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--
Eric S. Perlman, Associate Professor 		eperlman@fit.edu
Physics and Space Sciences Department		Phone:  +1 321 674 7741
Florida Institute of Technology		     	Fax:    +1 321 674 7482
150 West University Boulevard Melbourne, FL 32901