Results of the Grazing Occultation of Aldebaran

October 19, 2016

 

 

 

 

Observer List and Observation Details

Sorted by Decreasing Latitude - Positions have been rounded off

Click Observer Name link to go directly to their data

 

Observer Location Latitude (N) Longitude (W) Elev (m) Telescope Mount Camera VTI
Martin Gormanson River Falls, WI 44.8370 92.6250 288 4" refr EQ Canon T3i Derived Time Data
Richard Nolthenius Apple Valley, CA 34.4955 117.1549 896 20 cm, f/10 SCT EQ Watec 910HX IOTA-VTI
Chuck McPartlin Apple Valley, CA 34.4946 117.1553 896 13 cm, f/6.5 refr EQ Mallincam MCHP Color IOTA-VTI
Walt Morgan Apple Valley, CA 34.4939 117.1553 896 20 cm, f/10 SCT AltAz PC164CEX-2 IOTA-VTI
Derek Breit Apple Valley, CA 34.4907 117.1552 895 8 cm, f/10 refr EQ Watec 902H IOTA-VTI
Greg Lyzenga San Gabriel Canyon, 34.2121 117.8632 505 20 cm, f/10 SCT EQ PC164CEX2 STV Astro
                 

SCT= Schmidt-Cassegrain  RC=Ritchey-Chretien  Dob=Dobsonian  Refr=Refractor                AltAz=Altitude-Azimuth   EQ=Equatorial              KIWI=KIWI-VTI    IOTA=IOTA-VTI

 

 

All Observer Profile from Occult

 

All Observers Profile with LOLA points

 

Profile Analysis by Mitsuru Soma

 

Enlarged Image to show Details and the Effect of Libration

 

 

 

 

Martin Gormanson (derived time data)  YouTube video

Light Curve from Excel

 

Fit of Observations to Profile from Occult

 

Light Curve with Profile

 

 

Richard Nolthenius  YouTube video

Light Curve from Excel

 

Fit of Observations to Profile from Occult

 

Light Curve with Profile

 

 

 

Chuck McPartlin   YouTube video

Light Curve from Excel

Beginning affected by small image scale and proximity of bright lunar limb

 

Fit of Observations to Profile from Occult

 

Light Curve with Profile

 

 

 

Walter Morgan   YouTube video

Light Curve from Excel

 

Fit of Observations to Profile from Occult

 

Light Curve with Profile

 

 

 

Derek Breit    YouTube video

Light Curve from Excel

 

 

Fit of Observations to Profile from Occult

 

Light Curve with Profile

 

 

 

Greg Lyzenga

Light Curve from Excel

 

Fit of Observations to Profile from Occult

 

Light Curve with Profile

 

 

 

 

Discussion of Results from Dave Herald

 

Note in the image below that the apparent lines of the data points are not satellite scan lines.

Rather they are indicative of the data resolution, which is 0.02 in D (which may be thought of as being the distance in-front-of/behind the limb).

 

 

The other interesting thing is that the reduction shows the residual as  -0.04" 0.02". Small but significant.

However if you do a star catalogue comparison in Occult (HIP 21421) you find the formal uncertainty

in the Hipparcos position of Aldebaran at current epochs is 0.021 in RA and 0.017 in Dec.

Interestingly UCAC4 (which uses Hip for the bright stars) lists an uncertainty of 0.026.

So the observed displacement is almost certainly explained by the uncertainty in the position (actually, proper motion) of Aldebaran.

 

And from the July 29 Aldebaran graze:

The formal solution for the July 29 graze is exactly the same: 0.04 0.02. And both grazes are at a similar PA - ~345.

Definitely a star position issue, with Aldebaran being a little south of the Hipparcos position.