AAVSO Alert Notice 429
Photometry requested for three Vestoid Near-Earth Objects
January 7, 2011

Dr. Michael David Hicks (Jet Propulsion Laboratory) contacted the AAVSO requesting precision photometry of three solar system objects in support of NASA’s DAWN mission to Vesta. These objects, called “Vestoids”, are near-Earth objects with similar reflectance spectra to Vesta itself, suggesting they may be fragments of that larger body. Broad-band photometry may help constrain object sizes and compositions.

The three objects are 1981 Midas (1973 EA), 4688 (1980 WF), and 137052 (1998 VO33). Hicks and collaborators are hoping to obtain photometry at the 0.1-magnitude level or better of all three objects during some or all of the first three months of 2011. All are fainter than 16th magnitude throughout their apparitions during this time frame. All will move perceptibly during the course of an observing run; observers with mounts that track sidereally should keep exposure times short (30s or less is likely) to make sure the asteroid does not move outside their photometric aperture during each exposure. Multiple exposures will likely be required to reach the required signal to noise for most observers, and 4688 (1980 WF) will likely be beyond the capabilities of most telescopes by early March 2011.

The following three tables list the ephemerides for these three objects computed from known orbital parameters computed in intervals of five days beginning 2011 January 07 (JD 2455568). Magnitudes in the tables are V. Observers are asked to observe these targets in the Rc filter if possible; V filter observations are also acceptable.

We note that since these are solar system objects, they are not included in the AAVSO International Database. Observers are asked to communicate their photometry directly to the PI (michael_david_hicks@yahoo.com , or Michael.Hicks@jpl.nasa.gov). However, please email Elizabeth Waagen (eowaagen@aavso.org) so that we know that you’ve participated.

Table: Ephemerides of Vestoids 1981 Midas, 4688, and 137052


1981 Midas (1973 EA)
———————————-    ———–    ———–    —–
JD 2455568.5 (2011 01 07 00:00 UT)    13:53:35.54    +11:45:51.8    18.17
JD 2455573.5 (2011 01 12 00:00 UT)    14:06:16.59    +09:24:34.8    17.97
JD 2455578.5 (2011 01 17 00:00 UT)    14:20:03.27    +06:41:24.1    17.76
JD 2455583.5 (2011 01 22 00:00 UT)    14:35:19.35    +03:30:00.7    17.54
JD 2455588.5 (2011 01 27 00:00 UT)    14:52:38.15    -00:17:25.8    17.33
JD 2455593.5 (2011 02 01 00:00 UT)    15:12:46.58    -04:50:04.3    17.12
JD 2455598.5 (2011 02 06 00:00 UT)    15:36:51.77    -10:16:48.4    16.93
JD 2455603.5 (2011 02 11 00:00 UT)    16:06:28.21    -16:41:30.2    16.78
JD 2455608.5 (2011 02 16 00:00 UT)    16:43:38.21    -23:53:02.2    16.70
JD 2455613.5 (2011 02 21 00:00 UT)    17:30:25.55    -31:12:04.8    16.71
JD 2455618.5 (2011 02 26 00:00 UT)    18:27:23.30    -37:28:39.7    16.81

4688 (1980 WF)
———————————-    ———–    ———–    —–
JD 2455568.5 (2011 01 07 00:00 UT)    02:59:36.81    -03:22:50.7    17.81
JD 2455573.5 (2011 01 12 00:00 UT)    03:25:34.85    -04:09:27.1    17.80
JD 2455578.5 (2011 01 17 00:00 UT)    03:52:54.77    -04:39:08.2    17.81
JD 2455583.5 (2011 01 22 00:00 UT)    04:20:54.35    -04:51:06.4    17.84
JD 2455588.5 (2011 01 27 00:00 UT)    04:48:49.58    -04:45:34.8    17.89
JD 2455593.5 (2011 02 01 00:00 UT)    05:16:02.69    -04:24:08.8    17.97
JD 2455598.5 (2011 02 06 00:00 UT)    05:42:05.09    -03:49:51.3    18.08
JD 2455603.5 (2011 02 11 00:00 UT)    06:06:37.78    -03:06:31.1    18.21
JD 2455608.5 (2011 02 16 00:00 UT)    06:29:30.93    -02:17:54.7    18.37
JD 2455613.5 (2011 02 21 00:00 UT)    06:50:42.30    -01:27:13.9    18.55
JD 2455618.5 (2011 02 26 00:00 UT)    07:10:16.15    -00:36:55.2    18.75
JD 2455623.5 (2011 03 03 00:00 UT)    07:28:21.88    +00:11:02.4    18.96
JD 2455628.5 (2011 03 08 00:00 UT)    07:45:10.33    +00:55:03.7    19.18
JD 2455633.5 (2011 03 13 00:00 UT)    08:00:51.66    +01:34:02.4    19.41
JD 2455638.5 (2011 03 18 00:00 UT)    08:15:34.59    +02:07:21.5    19.64
JD 2455643.5 (2011 03 23 00:00 UT)    08:29:26.43    +02:34:49.5    19.87
JD 2455648.5 (2011 03 28 00:00 UT)    08:42:34.18    +02:56:27.9    20.10
JD 2455653.5 (2011 04 02 00:00 UT)    08:55:04.76    +03:12:20.1    20.33
JD 2455658.5 (2011 04 07 00:00 UT)    09:07:03.98    +03:22:33.5    20.55
JD 2455663.5 (2011 04 12 00:00 UT)    09:18:36.30    +03:27:22.1    20.77
JD 2455668.5 (2011 04 17 00:00 UT)    09:29:44.96    +03:27:06.8    20.98

137052 (1998 VO33)
———————————-    ———–    ———–    —–
JD 2455568.5 (2011 01 07 00:00 UT)    10:23:06.56    +40:55:58.2    18.23
JD 2455573.5 (2011 01 12 00:00 UT)    10:19:55.44    +44:31:16.6    17.91
JD 2455578.5 (2011 01 17 00:00 UT)    10:13:16.27    +48:50:09.6    17.59
JD 2455583.5 (2011 01 22 00:00 UT)    10:01:04.83    +53:56:42.0    17.31
JD 2455588.5 (2011 01 27 00:00 UT)    09:39:11.56    +59:48:30.4    17.09
JD 2455593.5 (2011 02 01 00:00 UT)    08:58:36.57    +66:04:33.5    16.94
JD 2455598.5 (2011 02 06 00:00 UT)    07:40:47.03    +71:35:15.0    16.88
JD 2455603.5 (2011 02 11 00:00 UT)    05:32:19.70    +73:38:09.0    16.90
JD 2455608.5 (2011 02 16 00:00 UT)    03:28:39.34    +70:08:07.9    17.02
JD 2455613.5 (2011 02 21 00:00 UT)    02:14:53.75    +63:07:13.6    17.22
JD 2455618.5 (2011 02 26 00:00 UT)    01:33:31.10    +54:58:06.9    17.51
JD 2455623.5 (2011 03 03 00:00 UT)    01:07:31.07    +46:41:56.6    17.90

This AAVSO Alert Notice was prepared by Matthew R. Templeton.

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