Comet Leonard Jan 8

[OzEclipse]

After a couple of days of rain and now with a 5.5 day old 37% illuminate waxing crescent Moon in the sky, Leonard is definitely harder to see. No naked eye sighting, easy in 8x50mm finder and 9x63 binoculars even in late twilight.

The nucleus is starlike in binoculars with a faint coma. 1.5 deg of tail visible with direct vision extending to perhaps 2.5 degrees with averted vision.

Using IN-IN estimation method with 9x63 binoculars, I estimated the nucleus to be about half way between these two stars perhaps a little closer to HIP108294.

HIP108294 {Mv 5.43}_____4/10______Comet_____6/10_____HIP 107079 {Mv 6.90}
6.90 - 5.43 = 1.47
4/10 x 1.47 = 0.59

Comet Leonard estimated brightness ~ Mv= ~ 6.0

Joe

[turboscrew]

What's "IN-IN estimation method"?

[OzEclipse]

What's "IN-IN estimation method"?

Hi Juha,

It's 3am, just came in from observing for many hours. After 2 days of rain, I can practically reach up and pluck the stars out of the sky.

There are many ways visual, instrumental, and photographic for measuring comet brightness. The two methods usually used by visual observers to estimate the magnitude of a comet are colloquially referred to as the IN-IN and IN-OUT methods.

IN-OUT. When the comet has a diffuse coma you observe the comet IN focus then defocus comparison stars until their image spreads out to the same diameter as the coma of the in-focus comet and observe them OUT of focus. Then using at least two stars, one brighter, one fainter, you estimate the ratio of where in the middle the comet sits compared to the two stars. I used this method previously when the comet had a large coma.

IN-IN When the comet has more of a starlike nucleus, you use the same comparison ratio method as above but with the stars IN focus and the comet IN focus.

The method is described in more detail in J.B. Sidgwicks Classic Text, "Observational Astronomy for Amateurs"

I have attached photos of the two pages that cover this technique

Time for bed.

Cheers

Joe

[Butterfly Maiden]

@OzEclipse Okay Joe, I am totally impressed by your technical knowledge, which BTW flew right over my head

I am quite certain that many of our members with a more technical brain than me understood everything you said.

I just like to look at your photos and appreciate their beauty from a visual perspective.

But please, be as technical as you want to be for the members who understand that information

[helicon]

Thanks for the update on Leonard Joe and very helpful information for observers. Congratulations on winning the TSS VROD for the day!

[Butterfly Maiden]

Congratulations Joe on receiving the TSS VROD award for your excellent technical information

[Makuser]

Hi Joe. A very nice observing report on Comet Leonard. And I also appreciated the accompanying information for the calculations. Thanks for sharing this report with us Joe and congratulations on receiving the TSS VROD Award today.

[John Baars]

Congratulations on the VROD!

[turboscrew]

What's "IN-IN estimation method"?

Hi Juha,

It's 3am, just came in from observing for many hours. After 2 days of rain, I can practically reach up and pluck the stars out of the sky.

There are many ways visual, instrumental, and photographic for measuring comet brightness. The two methods usually used by visual observers to estimate the magnitude of a comet are colloquially referred to as the IN-IN and IN-OUT methods.

IN-OUT. When the comet has a diffuse coma you observe the comet IN focus then defocus comparison stars until their image spreads out to the same diameter as the coma of the in-focus comet and observe them OUT of focus. Then using at least two stars, one brighter, one fainter, you estimate the ratio of where in the middle the comet sits compared to the two stars. I used this method previously when the comet had a large coma.

IN-IN When the comet has more of a starlike nucleus, you use the same comparison ratio method as above but with the stars IN focus and the comet IN focus.

The method is described in more detail in J.B. Sidgwicks Classic Text, "Observational Astronomy for Amateurs"

I have attached photos of the two pages that cover this technique


Time for bed.

Cheers

Joe

THANKS! You always learn something new.

[OzEclipse]

Thanks for the update on Leonard Joe and very helpful information for observers. Congratulations on winning the TSS VROD for the day!

Thank you Michael. I am still a bit bleary eyed after last night. After the comet set, I took advantage of the clear clean air after the rain and did some bino deep sky observing in Auriga, low in the north from here.

Joe

[Bigzmey]

Nice that Comet Leonard is still within your reach and you are keeping track of its progress, Joe.