Observing Instructions

Thanks very much for agreeing to get involved in our observing campaign of young star PDS 110!

The paper, the newly created website, and the AAVSO campaign page should tell you a bit about why we’re observing this object, but here’s some vital info:

• Central eclipse time = HJD=2458015.5 ± 10 (Sept 9-30 2017).
• Depth = 26±6%
• Duration( where dip depth>2%) = 16±5 d
• Probability of eclipse = uncertain. Likely >75%?

Until the dip begins, we require only a minimal amount of photometry – one or two points (or series of points) per scope per night is sufficient. Orion is observable for more than an hour before dawn at most locations currently, so this can begin right away (and some of you are already observing!).

If and when the dip begins, we will send out an email to this list and ask for increased coverage – either by taking many more points or by observing continuously (if possible). Alternatively, observatories have the option of beginning observations at this trigger.

Filters: For telescopes with a filter wheel, we ask for multiple filters with as wide a wavelength coverage as possible as this should allow us to constrain the dust grain size of the eclipsing object.

Because of the disparate array of telescopes, we ask each observer to reduce their data separately and to contribute only the final light curve. Professionals likely have their own reduction pipelines on hand, which should work great.

For amateurs, AAVSO has specified some good comparison stars which, if used by everyone, should give consistent results. The list of these can be found here, with a 30’ finder chart here.

We ask observers, both amateur and professional, to upload data to the AAVSO WebObs tool. You will need to register as a user and then “generate an Obscode” to be able to submit data. Then, users must upload an ascii file following the extended file type format.

If this is not possible, we will also use this google spreadsheet to collate data (using a similar file format).

To monitor the star in near-real time, we would ideally like observations reduced and uploaded within a few days (or at most a week).

We will be posting plots light curves from AAVSO, LCO, and any other observations we have in a few places – in the “lightcurves” thread of the Slack channel (please email me if you would like to join this), in the Latest Data page on the website, and in the google doc.

All major contributors of photometry shall receive co-authorship on the eventual follow-up paper (this will happen regardless of what we observe). If contributing observatories require additional co-authors or acknowledgements, please let me know.

Finally, if you have any questions feel free to email me on hugh.osborn {AT} lam.fr . And certainly, if you know anyone else who would be interested, point them towards the AAVSO campaign or the website.