The 1.5 m solar telescope GREGOR at the Observatorio del Teide is now fully operative. It observes the photosphere and chromosphere in the visible and near infrared with three post-focus instruments. One of them is a grating spectro-polarimeter for the near infrared (1.0 to 2.2 um) called GRIS. This instrument is working perfectly and last two months have been providing spectropolarimetric data at 1.5 um in the infrared at a spatial resolution comparable with Hinode (about 0.3") and with equivalent spectral resolution. This is the first time a solar facility records spectropolarimetric data with 0.3" spatial resolution in the near infrared. This is posible thanks to the multi-conjugated adaptive optics system installed at GREGOR (right now it is working in "adaptive optics" mode on only. We expect to have the full system working properly soon) and the 1.5m clear aperture.
The data we have recorded so far are excellent. However, before going into the detailed analysis of these data, we want to make a direct comparison of the near-infrared data with similar spectropolarimetric observations in the visible. This is why we need Hinode to obtain spectropolarimetric maps at 0.3" resolution and in the 630nm visible spectral lines. These data would greatly help evaluate the performance of GRIS and moreover, will provide invaluable scientific input for the solar community since, for the first time, we will have the opportunity to analyze the solar atmosphere using visible and IR lineas at such spatial resolutions.
Some of the GREGOR functionalities are now being tested and so far we are putting all efforts in observing sunspots and Active Regions in the 1.5 um spectral band which contains several Fe I lines with very large lande factors. Thus, we would like to request the following:
Time: From 9 UT to 12 UT and from 15 UT ato 17UT.
SP spectropolarimeter: Maps of 80" x 80" with 0."16 resolution (single side). As many as possible within the time windows, depending on telemetry.
BFI: Ca II and Blue continuum, similar FOV, 1 minute cadence. The evolution is not so important so if telemetry is limited please reduce the cadence to 5 minutes or less.
The observation should be concentrated in Sunsports near disk center (if possible). There is an AR coming AR12096 which may be a good target. The pointing should be the umbra of the selected sunspot. The reason is that the performance of GREGOR is much better if we lock the AO system in sunspots. The FOV is limited by the GRIS slit length which is about 80 arc seconds. The times are related with: 1- better seeing conditions at GREGOR in the little experience we are having this year with the telescope and 2- the image rotation at GREGOR is minimized at these times, ensuring a better polarimetric performance of GRIS.
We hope, that in 7 days we are lucky with the seeing conditions and we can get simultaneous observations. We think this will be possible since seeing conditions are quite relaxed at 1.5 um and AO system is working impressively well.
Finally we would like to ask for a special request. We have been also observing at 1.0 um (He 1083 nm) but observations in this line are slightly harder. One of the reasons is that although we have a H alpha slitjoe imager, it is not working at expected (we are replacing it). So, we would like to have on 28 July an observation with the SP 80" x 80" and several snapshots in the H alpha NFI channel. We thing that, even if the seen is not that good one day, the information will be very important to check the performance of GRIS at the 1083nm line. The target should be a sunspot near disk center. |
|