2023 January 28 05:09UT – Comet 29P/Schwassmann–Wachmann 1

This event involves Comet 29P/Schwassmann–Wachmann 1. This Centaur is very likely from the Kuiper Belt. Compared to other Centaurs, Comet 29P/S-W 1 is in a relatively close-in, circular orbit that varies between just 5.72-6.25 AU from the Sun. At this close distance, the object is actively outgassing volatiles and flares in brightness roughly every other month by as much as 1-5 magnitudes.

In collaboration with researchers in the UK, we have four opportunities to contribute to measuring this unique object during December and January.

A recent positive occultation supports that we have a good ephemeris for this object, and we hope to deploy teams from north and south of Yakima to attempt a multichord detection on the main body. The interactive map below shows the current prediction (dark blue), 1-sigma uncertainty (light blue), and the eight planned chords being covered by teams from Maupin, The Dalles, White Swan, Yakima, Ellensburg, Wenatchee, Chelan, and a team from CanCON!

Event Details

Visit the Event Detail Page for Comet 29P/S-W1 for information on exposure time, star location, and recording window. Note the the star chart on the event detail page shows the orientation of field as it appears on a MallinCam system rather than a QHY system. For the QHY field of view, you can rotate the star chart.

Pre-event Checklist

  • This is a targeted campaign and we are already in touch with RECON teams that are close enough to the predicted shadow path to participate.
  • Make sure to charge your laptop and battery pack fully. Verify that systems are charged. This is easy for the laptop but sometimes the battery packs can be confusing and aren’t really charged when you think they are.
  • Print this page or have it available by some electronic means that does not require a data connection. Many sites are remote and may not have cell phone coverage.
  • Make sure your laptop is in airplane mode during data collection.

Feel free to contact the RECON leadership team anytime by emailing tnorecon-org@mailman.boulder.swri.edu.

Observation Protocol

Make sure to log your observations (any data that are saved) either on a RECON logsheet (to be scanned later) or on an electronic file. Details about operating the camera and saving data can be found in the guide. Here are some reminders about the logsheet contents:

  • Use one entry per dataset (series of images) collected.
  • Use the UT time (HH_MM_SS) as shown on the green banner on the top of the screen at the end of the capture as the label in the left-most column on the logsheet.  Don’t use an approximate time from some other means.  This is used for finding the files, not documenting the time. If you miss the banner, you can browse the disk to find the folder that was written.
  • Make sure to write down the observing location (lat/lon/alt) of your site on the logsheet. It is best to use a cell phone GPS app, not the SharpCap information for this position as a backup for the position.
  • The telescope name is the community name for that telescope (eg., Klamath Falls), the laptop id is the RECONxx number on the lid, the camera and the batteries have their own id codes as well.
  • Make sure to write down the FULL names of all team members on the logsheet. This is easiest if everyone writes down their own name. This is used for credit in the publications.
  • Do not use a logsheet on more than one night. Start a fresh one each night, and don’t expect that the information you provided on a previous night is good enough.  Fill them out completely each night.

Prediction map


KML files are available. In this area is a single file with the prediction and all the tracks. In the tracks sub-folder, there are individual files, one per track. You can use these with map programs on your cell phone to assist with navigation to the assigned location. The goal is for each team to be within +/- 500 m of their assigned track.

Weather Prediction Tool

Available at the link below, Kai Getrost has provided a very useful weather prediction tool for monitoring forecasts relevant to this campaign.

Finding Charts

See Event Detail Page.

Image of Field

Image of field with the orientation at the time of the event, matching the standard RECON QHY FOV and scale. Note that on event night, the target star will appear somewhat brigher and slightly fuzzy due to the coma of the occulting body.

HyperStar image of field, not at rotation of field at the time.

Important Reminders

  • Control lighting – laptop screen or flashlights should not shine on the front of the telescope tube. You can’t do anything about the moon but you don’t need to make it worse.
  • Keep target star somewhat near the center.  Use the lowest rate possible for guiding.  It should be very slow so that there is minimal to no smearing of the image during an exposure.  Rate 1 works best most of the time but may not be enough if working near the zenith.  The ideal is to not use any guiding corrections at all.
  • Vigilance is required while collecting data.  Tracking is usually quite good with the RECON telescopes but its behavior can change.  You will have to determine a safe interval between checks if constant supervision is not possible.
  • Arrange the field placement to get the target star near the center of the frame throughout.  However, nice placement of surrounding field stars is more valuable than perfect centering of the target star.
  • The laptop does not sleep or hibernate. Closing the lid does nothing. To turn the computer off you must explicitly command Windows to turn the power off.
  • You can change the display stretch (lightning bolt symbol on Display parameters tab) even while collecting data.
  • If the GPS status says “Bad data” you must fix the situation. Without GPS data support, the data are indeed bad. If this happens after enough of a wait that it should already be locked, the first thing to try is to change the exposure time to some other value and then change it back to the initial 500 ms value.
  • For the 1-2 minutes around the predicted mid-time, do not guide at all unless it is really, really necessary.

Post-Event Details

Regardless of whether your team was able to collect data, we need all teams to provide a log of their efforts. This will include details of data if your team collected data. Either save the electronic version of your log sheet and upload both your videos and observation log with your data to uploaded to SwRI in Boulder or send it via email to the project leader. For more information procedures for uploading data, visit Reporting Observations. Special arrangements will be made upon request for uploading non-RECON system data.