MCP telecon: Jan 5, 2011
Attending: Jim B, Jim C, Cheng-Yu, Mark, Christian
New analysis of accelerations results in much improved distance. Over 6 epochs, the systemic spectrum appears to show three distinct maser clusters. Cheng-Yu's approach is to assume a single acceleration applies for all the masers within each group. Ho modified Mark's program to fit a single accel, and fits the three groups separately. The first two groups show accel ~ 0.9 and 1.1 and these are used in the distance measurement. The third group (at the high-velocity end of the systemic spectrum) has a ~ 5 and is not used in distance calculation. The PV diagram is consistent with this interpretation. Now have distance to 11%!
Mark points out that a serious limitation remains in modeling the disk and he is trying to get Jo Bovy (NYU) interested in the problem. Jo is a Bayesian modeling expert and would be valuable.
- Violetta will present poster at AAS
Her poster will show VLBI maps of all galaxies we've observed so far.
Mark notes that the data processing has been complicated by peculiarities in the data. Took ~ 1 week to process one track but the others should go quickly. The map is similar to the first. Plans to combine all tracks to improve PV diagram. Mark offered a word of warning: his first attempt to map included a restricted FRING window for measuring single-band delays, and this caused the disk to appear in an E-W orientation which he knew was wrong. He later found that opening the search window for GBT and EB fixed the problem. Would not expect to see this problem if he incorporated the geodetic corrections first -- which he intends to do anyway.
- Update on VLBI observations
We are having troubles completing the N6424 VLBI plans. It is unclear whether the GBT was recording properly for the track observed Dec 30, 2010. Top priority remains to get the remaining tracks observed on N6264, After that we will observe ESO 558-G009 (which wil not include EB since it is Dec = -21)
- Update on GBT surveys and monitoring
Jim B continues to work on generating target lists from 2MRS. So far he is just
keeping up with the osbervations being scheduled. Expect soon to circulate a web page with a compendium of all GBT observations this year.
The focus of the workshop will be on how to reduce costs of VLBA without sacrificing science. We will emphasize our science and mention several potential cost savings measures. (1) The MCP could lose several antennas without losing science, e.g. SC and two or three southwestern antennas. (2) We could have an annual shutdown during summer. We should present the science and requirements foremost.
Jim B will work with Christian to determine whether we need to submit a new EB proposal for Feb 1 deadline.
- EVLA proposal to look for continuum (jet) emission: Feb 1 deadline. Idea is to measure orientation of jets in galaxies with disk masers, and detect continuum to see if we can also eventually hope to measure VLBI continuum for locating the BH. Christian will have time to prepare a first draft during 3rd week of January.