[Cymraeg]

Physics projects for Y3 and Y4 students


Project description

Optical SETI

(supervisor: Tony Cook)

Nature of project: experimental, data analysis

Available to students on full-time physics degree schemes or joint students.

Project description and methodology

Although the Search for Extraterrestrial Intelligence (SETI) has been mostly attempted using Radio Telescopes, there are some efforts to undertake optical searches for evidence of Laser Communications, Star Ship Light Drives etc. The purpose of this project is not to find E.T. but to demonstrate Optical SETI.

You will utilize one or two remotely operated telescopes, one at Fron Goch and the other on top of the Physics building to take low light sensitive camera video of the same parts of the sky. For example concentrating on a region of sky containing a globular star cluster, or stars known to have terrestrial type planets in the habitable zone. You will capture video over many hours from both telescopes, and feed this through flash detection software which has been used to find impact flashes on the Moon, or cosmic ray decay particles in CCD cameras.

False Flashes can be caused by image noise, radiation events from cosmic ray air showers, from meteors, from car headlights/lightening illuminating dust particles in the air, or even from sun glint from satellites passing through the field of view. Ways need to be found to tell the difference between these and real Optical SETI flashes. Using two telescopes will help to eliminate many of these false effects.

You should look at signal to noise ratio and determine what magnitude limits flashes can be detected at, and produce a frequency distribution plot of their brightness to show how it might be possible to discriminate from background image noise, and how you would go about setting detection thresholds.

A successful project will develop beyond the above in one/some of the following directions:
1) Use two telescopes, at different locations, to eliminate most of the false flash effects mentioned above. But we would like to know how common these are compared to the remaining flashes which appear in both scopes.

2) Experiment using a diffraction grating to learn something more about flashes which are seen simultaneously in both telescopes. Perhaps it's a discrete wavelength e.g. a Laser emission, or maybe a blackbody curve?

3) To illustrate the diffraction grating aspect of the project, you can try (after carefully checking for aircraft etc) shining a laser pointer at the region of sky that the telescope is pointing at, and attempt to detect back scatter of particulates in the atmosphere along the telescope line of sight. Particles moving through the narrow beam of the laser, could appear as brief flashes of light to the telescope. Alternatively see if you can detect flashes from satellites equipped with LIDAR. Satellite passages can be found on the http://www.heavens-above.com/ web site.

4) You should demonstrate looking for flashes from short duration, e.g. from a few seconds, down to one TV frame or field i.e. 1/25 or 1/50th sec.

When considering where to take your project, please bear in mind the time available. It is preferable to do fewer things well than to try many and not get conclusive results on any of them. However, sometimes it is useful to have a couple of strands of investigation in parallel to work on in case delays occur.

Additional scope or challenge if taken as a Year-4 project: Optical SETI researchers have suggested that laser flashes could be very short duration e.g. 1 microsec to 1 nanosec.

Although our cameras have a shortest exposure of 1/2500th sec, by slewing the telescope at 2 deg per sec (assuming an image scale of 1"/pixel), we can obtain an effective time resolution of 0.1 microsec.

The down side is reference stars will be significantly trailed, and so we lose the ability to fix the position of a flash in azimuth direction, but we do at least achieve the necessary time resolution. Adding a diffraction grating will help give wavelength specific information and help us discriminate cosmic ray events.

Please speak to Tony Cook if you consider doing this project.

Initial literature for students:

  1. M. Schuetz, D. Vakoch, S. Shostak, and J. Richards (2016) O SETI OBSERVATIONS OF THE ANOMALOUS STAR KIC 8462852, The Astrophysical Journal Letters, Volume 825, Number 1
  2. Abeysekara, A.U., et al., A SEARCH FOR BRIEF OPTICAL FLASHES ASSOCIATED WITH THE SETI TARGET KIC 8462852. Astrophysical Journal Letters, 2016. 818(2): p. 6.
  3. Groom, D. (1998) Cosmic Rays and other Nonsense in Astronomical CCD Imagers, http://snap.lbl.gov/ccdweb/groom.pdf
  4. Bhathal, R., The case for optical SETI. Astronomy & Geophysics, 2000. 41(1): p. 25-26.

Novelty, degree of difficulty and amount of assistance required

This is of similar difficulty to the lunar impact flash observing project, however you are not constrained by having to wait for the Moon to be about.

Project milestones and deliverables (including timescale)

milestoneto be completed by
Extensive evaluation of different optical SETI techniquesend of October
Select some target areas of the skyChristmas
Extensive observations in terms of hoursend of February
Finish flash detection in the video captured and evaluate the false detections and any remaining candidate detectionsEaster

Students taking this project will have to submit a full risk assessment form