Photometry log #4: end of campaign

lco_quesos-page-001_cropped — Percentage of observed and lost nights with LCO for the three Red Dots 2017 targets: Proxima Centauri, Barnard's star and Ross 154.

Time has flown so fast! It has been more than a 100! days since we started the photometric follow-up of the three RedDots2017 objects back in mid June. HARPS spectroscopic observations are just over, and the photometric observatories are about to wrap up too! And this is what they report:

Las Cumbres Observatory (LCO)
The observing campaign started the 14th of June of 2017 and has been gathering
data for more than 100 nights. All the three stars were observed each night for 15 minutes continuously with the 40 cm LCO telescopes located in Australia (Siding Spring Observatory), Spain (Tenerife, Teide Observatory) and the United States (Hawaii, Haleakala Observatory). Proxima Centauri was observed from Australia, Barnard’s star was observed from Australia, Spain and USA, while Ross 154 was observed from Australia and USA. Initially, we had the intention of using also a telescope in Chile (Cerro Tololo Observatory), but eventually it was used by LCO to track satellites and could not participate in the Red Dots campaign.

Figure 1. Percentage of observed and lost nights with LCO for the three Red Dots 2017 targets: Proxima Centauri, Barnard’s star and Ross 154.

Proxima Centauri was observed for a total 97 nights starting on June14th until September 18th, when the star ceased to be visible from Australia. Of a total of 97 nights, we could obtain data on 65 of them, i.e. a 67% percent of success. Most of the lost nights were due to poor weather conditions at Siding Springs Observatory.

Currently, we are still taking data for Barnard’s star and Ross 154: as of October 4th, we have been gathering data for 113 nights. We were able to obtain data for Barnard’s star on 95 nights out of 113, while on 83 nights out of the same total, for Ross 154, giving an 84% and 73% of success rate, respectively (see Fig. 1).

Montsec Astronomical Observatory (OAdM)

Figure 2. Light curves of Barnard’s and Ross 154 obtained at TJO in V, R, I filters. After a time baseline of 80 days, no significant signal is found yet in the Barnard’s data, which is measured to have a rotation period of ~130 days. More data are still being acquired to confirm the rotation period.

The Joan Oró telescope (TJO) has been monitoring Barnard’s star and Ross 154 for more than 100 nights now. The TJO acquired Red Dots data for a total of 68 nights, resulting on more than 1200 images for Barnard’s star in R and I filters, and about 500 images for Ross 154 in V, R and I filters. Most of the lost nights occurred during late August and September due to bad weather conditions. Also, some high priority observations at the beginning of the night prevented us to observe Ross 154 for several weeks. A sample of the light curves obtained up to September 2017 is given in Fig. 2.

The TJO will keep observing both targets until the end of their observability period to have the longest possible time baseline to find signals of activity in the light curves.

SPACE Observatory

Figure 3. Light curve of Proxima Centauri after the first 50 nights of observations in ASH2 with V (blue) and R (red) filters. The estimated rotation period for Proxima Cen is 83 days. More data are still in the reduction process to refute or confirm the rotation period.

The ASH2 telescope at SPACE Observatory started the follow-up of the 3 Red Dots targets on June 18th. Of a total of 110 nights, 35 were unfortunately lost due to technical problems. As you may remember from our previous post, observations had to be stopped on August 7th and could eventually not resume until September 10th. Figure 3 shows Proxima Centauri’s light curve obtained up to the halt due to the technical problem.

Another 17 nights were lost due mainly to clouds, so that leave us with successful rates of observing varying between about a 40 and a 50%.

ASH2 has stopped following Proxima, as it is already too low to get useful data, however, it will still acquire data on Ross 154 until October 15th.

Sierra Nevada Observatory (SNO)
The 90 cm telescope has been observing Barnard’s star since June 11th. From a total of 117 nights, we lost about half of them, mainly due to clouds (33 nights), wind (12), other observing programs (7), technical maintenance (6) and also Saharan dust (3).

Figure 4. Barnard’s light curve obtained at SNO in the R filter. A first analysis does not find any significant signal, although data are still not complete. Barnard’s is a quiet star with an estimated rotation period of ~130 days.

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This is the news and some preliminary analysis from the different observatories so far. Photometric follow-up will finish in the following couple of weeks and it will be time to put all the data together and do thorough analysis of all of them. We will closely look at any promising signal in the spectroscopy to be detected in the photometry, pointing at activity processes instead of a planet signature… but this would make the case of another photometry log… Stay tuned!

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