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Ursa Astronomical Association

Exoplanet HIP 41378f - 13.11.2022 at 23.25 - 14.11.2022 at 04.37 Janakkala, Tervakoski Observation number 110903

Visibility I / V

Petri Kuossari, Riihimäen tähtit. yhdistys

I had the honor of starting to observe the transit of a Saturn-like exoplanet from Tervakoski, Finland, on November 13. It was unusually warm at night +9 degrees and there was a strong storm. I looked for a sheltered spot for my telescope at the end of the horse stable.

HIP 41378 f is what astronomers call a "super-puff" planet, meaning it's big, but its density is predicted to be very low. The planet orbits its star every 542 days

The planet is of particular interest because scientists believe it may have rings and perhaps even moons, just like Saturn in our own solar system. The Hubble Space Telescope made observations of HIP 41378 f in 2021 to determine the composition of its atmosphere, but it didn't gather any usable data - strange when the planet is so "bloated". This major oddity led astronomers to think that this exoplanet might have rings that make it appear "puffier" than it actually is.

At first glance at the data, it was not certain that we were seeing the entry or exit of the overflow. Then we got a message from a collaborator at an Italian observatory who claimed he had a clean observation of the beginning of the transit. The vertical dashed lines in the figure (for the "expected" overrun) are based on their time of observation.

Somewhat surprisingly, almost all European observers experienced bad weather only a few minutes before the start of the overpass. This created a gap before our North American spotters could reach the target. There was an entrance in that opening. At the other end, the sun rose in Japan before the long crossing ended. As you can see, we had one data set that occurred partially during the ingress of the overflow. In conclusion, we were just unlucky with the weather and timing.

Now the good news, it was nice to see how great accuracy the data represents before and during the crossing. Those blue dots show that if the flyover had happened a little earlier or later, we could have seen it!

We will submit our data to the group that organizes the publication of the photometry of this campaign, let's see what happens.

We can try this again in about 1.5 years.

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Additional information
  • Observation target
    • Exoplanet
  • Designation
    • HIP 41378f
  • Constellation
    • Cancer
Technical information

Target: HIP 41378f

Observer's name: Petri Kuossari

Date: 2022 11 13

City: Janakkala, Tervakoski Finland

60.791885 N 24.630539 E

eVscope ID: 257ksz

Finland time UTC+3

Start/end of the observation: 23:25 to 04:37 Finland time

Dark frames 04:40-04:41

Exposure time 3550 ms

CAD 3550

Gain 0

RA 8h 26m 28s

DEC 10° 4' 49"

Bordle 4

+9 Celsius

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