BAA 2019-2020 Low Phase Angle Photometry Project (ARPS)

Sheridan Williams

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-------- Forwarded Message --------
Subject: BAA 2019-2020 Low Phase Angle Photometry Project (ARPS)
Date: Thu, 31 Oct 2019 22:15:01 -0000
From: Richard Miles <rmiles.btee@...>
To: Unnamed recipients <rmiles@...>

The 2019-2020 observing season is now well underway and as part of the Asteroids and Remote Planets activities, I am announcing some observing targets.
In the summer, I selected the most worthwhile asteroids as part of our Low Phase Angle Photometry project. The list below summarises our 2019 targets. A further 6 or more will be tackled during the first half of 2020 and I shall announce those in a few week's time.
The aim is to observe these objects using a V photometric filter both before and after opposition, and during the critical time when they happen to pass through a very low phase angle. In this way, we shall quantify the light-scattering properties of their surface regolith by measuring the extent of the so-called Opposition Effect, the shape of the Phase Curve, as well as derive an unambiguous Rotation Period for each.
Asteroid Opposition Minimum V
Synodic Period

Number Name Date Phase Angle Mag. Dec. Period U Class. Diam.

y m d °
° h rating

243 Ida 2019 Sep 01.0 0.15 13.6 -8 4.634 3 S 28
135 Hertha 2019 Sep 06.3 0.02 9.6 -7 8.403 3 Xk 78
5534 1941 UN 2019 Oct 01.7 0.17 14.2 +3 4.1 2 S 9
76 Freia 2019 Oct 27.5 0.16 12.0 +12 9.973 3 X 145
1343 Nicole 2019 Nov 06.7 0.15 14.4 +16 14.76 3- C 25
For some time now, we have had access to a network of telescopes around the world managed by the Las Cumbres Observatory (LCO)
This has been possible thanks to the assistance of the UK-based Faulkes Telescope Project and so remote imaging of these objects has been underway for a while.
This project requires observations close to opposition but poor weather, especially in the UK, can often mean we fail to obtain observations at these critical times. In recent years however, LCO has become increasingly effective in being able to catch objects at, or very close to opposition and so we have already managed to obtain coverage at opposition for the first four asteroids listed. A few observers have also used their own observatories to pursue the first three objects and we now have most we need by way of images of these in the bag.
V-filter observations of (76) Freia and (1343) Nicole are now especially needed. I therefore encourage observers to take a time-series of at least 15 minutes duration as part of this latest initiative. Please correspond offline if you manage to make a start on either of these objects. Thanks.
We also have a good number of V-filter images taken through mainly 0.4-m and 1.0-m aperture telescopes of the (243) Ida, (135) Hertha, (5534) 1941UN and (76) Freia. If you do not have access to a telescope of your own but would be interested in carrying out some photometry on these images, then do please let me know offline and you should be able to contribute to the work of the Section in that way. We use the software Astrometrica to do this analysis.
Clear skies!
Richard Miles
Director, Asteroids and Remote Planets Section

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