LTP Checklist for Flashes

The following are based upon the flow charts in Appendix 2 of the “Hatfield SCT Lunar Atlas – A digitally Re-mastered Edition”.

Definition: A “Flash” style LTP are not to be confused with impact flashes on the lunar night side, which are usually < 0.1sec in duration and are red. Instead they relate to pin-point flashes seen on the day side of the Moon, which might be single, or repeat, or may appear as a sparkly cluster.

Checks to do: You should follow these steps to eliminate non-LTP causes:

1) If it was in Earthshine, and was typically < 0.1 sec then it could be an impact flash (if it was red) or part of a cosmic ray shower being detected in your eye or CCD. Skip any further checks - not a LTP.

2) If it was on the dayside of the Moon and you wait long enough, does it repeat again? If so check an atlas, or images on line, of Full Moon illumination, to see if there is a bright, but tiny craterlet here. If so this is not a LTP but just chance views of this craterlet under brief good seeing.

3) Could it be a tiny mountain peak on the terminator, just poking through into sunlight, and again only seen during brief moments of good seeing?

4) Do you see flashes elsewhere, separated by hundreds of km apart? If so these are not LTP.

5) If it was recorded on video, please check neighbouring frames to make sure it was not from a passing aircraft or satellite.

Observing flashes: If the above suggest it might be a LTP or impact flash, then you should do as the following, to document fully the event:

1) If it was on the night side of the Moon, try to gauge its magnitude by pointing the scope at a nearby star of known magnitude, then switch to a low power eyepiece to try to identify the position against the lunar disk, then email details including the date and UT to the ALPO impact flash coordinator: Brian Cudnik on: bmcudnik @ gmail.com. No further action is needed.

2) If the flash was on the dayside or terminator area, then keep on watching for at least 10 minutes to see if the effect recurs.

3) Locate the position and estimate the brightness of the flash(es) by comparing with nearby point-like features, or stars on the lunar limb.

4) If it does recur, and it is not covered by any of the explanations in the check list above, please call, text or email the LTP coordinator below immediately.

5) Sketch or image the location of the flashes.

6) If it is a recurring flash, quickly telephone, text, or email a few astronomy colleagues to mobilize them – but do not tell them what you have observed, just the name of the lunar feature. This will avoid observational bias.

7) Return to the telescope and continue observing the area to see when the flashes stop.

8) When the night’s observing is over, write up your report, including images and sketches and email to the LTP coordinator. Please try to write the report as quickly as possible in case you forget details.

ALPO LTP coordinator: Dr Anthony Cook. Tel/Text +44 798 5055 681. Email: atc @ aber.ac.uk