Come join the friendliest, most engaging and inclusive astronomy forum geared for beginners and advanced telescope users, astrophotography devotees, plus check out our "Astro" goods vendors.
Come join the friendliest, most engaging and inclusive astronomy forum geared for beginners and advanced telescope users, astrophotography devotees, plus check out our "Astro" goods vendors.
So I went out tonight and tried to capture a change in the brightness of Betelgeuse.
20240224.5 UT
Visual
First I did a naked eye visual comparison of
Betelgeuse [Mv 0.5]
Hadar, [Mv 0.61]
Procyon, [Mv 0.34]
Achernar. [Mv 0.46]
Aldebaran was behind trees.
Assessment:
To my naked eye, Betelgeuse [Mv 0.5] seemed to be between Achernar [Mv 0.46] and Hadar [Mv 0.61] and at lest than 0.1 mag difference, any difference in the stars brightness was indistinguishable to my eye.
In 2019, Betelgeuse was very noticeably fainter than it should be and easily detectable to the naked eye.
Photometry
Then I captured exposures of: -
Betelgeuse [Mv 0.5]
Hadar, [Mv 0.61]
Procyon, [Mv 0.5]
using a fully manual 200mm f4 lens set to infinity with DSLR set to ISO100 1/8s
I may defocus and tape the focus and increase the exposure to 1/4s to even out the light field for future measurements.
The trick is to get the exposure of the stars somewhere in the middle of the grey scale. You definitely do not want the star saturated. By using such a short exposure, I can use a camera and tripod only. No tracking mount required.
I then used Lightroom to read RGB levels and I reduced the data. This is a crude but effective method of photographic photometry demonstrated by the linear regression of the brightness between the three stars that span only 0.15 mag. If Betelgeuse was not on it's nominal brightness, the point for Betelgeuse would not form a linear regression line with the other points. So for now, no change in brightness. The strange brightness numbers are because I converted the logarithmic base 2.512 magnitude measurements to a linear scale.
Joe Cali
Amateur astronomer since 1978...................Web site :http://joe-cali.com/ Scopes: ATM 18" Dob, Vixen VC200L, ATM 6"f7, Stellarvue 102ED, Saxon ED80, WO M70 ED, Orion 102 Maksutov, ST80. Mounts: Takahashi EM-200, iOptron iEQ45, Push dobsonian with Nexus DSC, three homemade EQ's. Eyepieces: TV Naglers 31, 17, 12, 7; Denkmeier D21 & D14; Pentax XW10, XW5, Unitron 40mm Kellner, Meade Or 25,12 Cameras : Pentax K1, K5, K01, K10D / VIDEO CAMS : TacosBD, Lihmsec. Cam/guider/controllers: Lacerta MGEN 3, SW Synguider, Simulation Curriculum SkyFi 3+Sky safari Memberships Astronomical Association of Queensland; RASNZ Occultations Section; Single Exposure Milky Way Facebook Group (Moderator) (12k members), The Sky Searchers (moderator)
Very interesting idea Joe and certainly worthy of today's VROD. You have coupled real science with naked eye observing! (And photometry)
-Michael Refractors: ES AR152 f/6.5 Achromat on Twilight II, Celestron 102mm XLT f/9.8 on Celestron Heavy Duty Alt Az mount, KOWA 90mm spotting scope Binoculars: Celestron SkyMaster 15x70, Bushnell 10x50 Eyepieces: Various, GSO Superview, 9mm Plossl, Celestron 25mm Plossl Camera: ZWO ASI 120 Naked Eye: Two Eyeballs Latitude: 48.7229° N
helicon wrote: ↑Sun Feb 25, 2024 3:14 pm
Very interesting idea Joe and certainly worthy of today's VROD. You have coupled real science with naked eye observing! (And photometry)
Many thanks Michael [@helicon]. I'll persevere with this project. If there is another dimming event in progress, I'll see if I can produce a light curve.
I wrote to my contact in the IRA, [Irish Republic of Astronomy] for his information sources. All he quoted was that it came from the President of the Irish Association of Astronomy.
Joe
Amateur astronomer since 1978...................Web site :http://joe-cali.com/ Scopes: ATM 18" Dob, Vixen VC200L, ATM 6"f7, Stellarvue 102ED, Saxon ED80, WO M70 ED, Orion 102 Maksutov, ST80. Mounts: Takahashi EM-200, iOptron iEQ45, Push dobsonian with Nexus DSC, three homemade EQ's. Eyepieces: TV Naglers 31, 17, 12, 7; Denkmeier D21 & D14; Pentax XW10, XW5, Unitron 40mm Kellner, Meade Or 25,12 Cameras : Pentax K1, K5, K01, K10D / VIDEO CAMS : TacosBD, Lihmsec. Cam/guider/controllers: Lacerta MGEN 3, SW Synguider, Simulation Curriculum SkyFi 3+Sky safari Memberships Astronomical Association of Queensland; RASNZ Occultations Section; Single Exposure Milky Way Facebook Group (Moderator) (12k members), The Sky Searchers (moderator)