AstroTortillaによる極軸合わせ – オフセット計算
前回の続きです。
AstroTortillaはLinuxのPlate SolvingソフトウェアであるAstrometry.netのラッパーソフトです。Astrometry.netをWindows上で動かすために、Windows上のLinux環境であるCygwinを使います。そのためインストールはややこしいはずなんですが、幸いにもその辺はセットアッププログラムが自動的にやってくれます。
ただ、Astrometry.netが使う星図データベースは、自分のカメラと光学系用に適切なものをダウンロードする必要があります。そうしないと膨大なデータベースをダウンロードすることになりますし、位置計算のときにもムダなデータベースを総当たりすることになり時間がかかってしまうからです。長焦点を使っている場合は必然的に大きなデータベースが必要で、おそらく計算時間の短縮のためにいろいろ工夫しないといけないと思いますが、うちの場合は焦点距離が350mm程度ですので、小さなデータベースですみました。
セットアップの詳細はTUTORIAL (IMAGING): Setting up and Using AstroTortilla for Plate Solvingに紹介されていますのでこちらを見ながら設定すればよいと思います(手抜き
で、うちの場合は撮影インタフェースを、いつも使っているAPTと連携させました。
AstroTortillaは撮影インタフェースとして、APTの他にもBackyardEOS、MaxIm DL、Nebulosityなどの撮影ソフトウェアと連携させることが出来るようです。
撮影ソフトウェアと連携させると、RAWファイルなどのフォーマットを自動的にAstroTortillaの読めるPPM形式に変換して読んでくれるので便利です。BackyardEOSや私のAPTなど、キヤノンのDSLR機を使って撮影している場合でも、CR2ファイルを自動的に変換して読み込んでくれます。
カメラ設定しておけば、あとはAstroTortillaが撮影を必要としたときに、設定した撮影ソフトウェアを制御して撮影してきて、そのままAstrometry.netによるPlate Solvingがはじまります。今回の極軸合わせの機能を使っている場合でも同様です。
露出時間は私の場合、WO71+Kiss X4、ISO6400で1秒で大丈夫でした。あまり長いと極軸が合っていない状態の露出なので星が点像に写らない場合がありよくないらしいです。それに、星がたくさん写ればよいというわけでもなさそうです。
極軸合わせはメニューのToolsからPolar Alignmentを選択します。
これの使い方ですが、Astrotortilla Tutorial and Reviewによると、
– まず方位のオフセットを計算する ー 赤道儀の方位を修正する ー 次に高度のオフセットを計算する ー 赤道儀の高度を修正する
となっていますが、上のダイアログのデザインからすると上下あべこべの順番です。方位を修正してから高度の計算をしたほうがいいのかどうかは分かりません。前回紹介したこの記事にあるように、方位と高度のオフセット量をまず計算させておいて、次に方位と高度の修正をまとめてやりたいところです。
オフセット量の計算は、ドリフト法の応用でやっているようですが、間に望遠鏡を動かしながら2枚の撮影をして、それぞれの赤経・赤緯から計算しているようです。方位を例にしたワークフローとしては以下になります。
ー 南の南中付近の星野にテキトウに望遠鏡を向ける。明るい星など選ぶ必要はない。明るすぎる星は却ってパターン認識を阻害するので避けた方が良いくらい ー measure azymuth errorボタンを押す ー 撮影と計算が終わるまで待つ
APTからAstroTortillaへの転送と準備に30秒くらい、私のPCではPlate Solvingにだいたい30秒前後かかっていますので、4分程度でそれぞれの計算ができ、方位・高度合計では、望遠鏡を南から東西へ振る時間も考えると、8分程度で計算が終了することになります。これを早いとみるか遅いとみるかですが、自分で判断しなくてはならないオフセット量が自動で計算出来るのが利点です。
計算が終わると下のようになります。
日本語フォントの関係か、度の文字が化けるので分かりにくいですが、この例ですと極軸が方位で3.18度、西に振りすぎということになります。
以上がAstroTortillaによる極軸オフセット量の計算ですが、ネットの情報によるとこのツールのオフセット量の計算はまだ精度の点で疑問があるとの話です。使えない、使うな、と言っている人もいます。修正していないのに2回計算させると違う値を表示するという情報もあり、実際私も昨日同じ現象を確認しました。3回取って平均化すればいいのかもしれませんが、それだと時間がかかりすぎです。バックラッシュが関係しているかもしれない、ということですが、今後精度アップして欲しいところです。
get viagra today viagra online purchase canada women on viagra order viagra super active generic viagra on craigslist
online pharmacy viagra prescription online sale of viagra in pakistan viagra 75 mg is generic viagra just as good do they have viagra for women
cialis diabetes cialis and grapefruit juice cialis 10 mg how long does cialis take cialis originale online forum
can you eat before taking viagra viagra online montreal viagra pills price viagra for recreational use best price for viagra
Hi, I do think this is an excellent blog. I stumbledupon it 😉 I’m going to come back
yet again since I bookmarked it. Money and freedom is the
best way to change, may you be rich and continue to guide others.
Look into my blog: CBD for anxiety
cialis pills for men cialis online canada buy cialis soft online cialis ebay cialis without insurance
10mg cialis review cheapest online cialis is there generic cialis buy real cialis canada is cialis safe for heart patients
Hi there this is somewhat of off topic but I was wanting to know if blogs use WYSIWYG editors or if you have
to manually code with HTML. I’m starting a blog soon but
have no coding knowledge so I wanted to get guidance from someone with
experience. Any help would be greatly appreciated!
Awesome issues here. I am very satisfied to look your article.
Thanks a lot and I’m having a look ahead to touch you.
Will you kindly drop me a mail?
vendita cialis online italia cialis for high blood pressure cialis online prescription buy cialis pay with paypal 2.5 mg cialis
comprare viagra online italia buy viagra from canadian pharmacy pfizer viagra 100mg cheap online viagra pills buy viagra online overnight shipping
viagra homemade danger of buying viagra online online viagra long term side effects of viagra 100mg viagra online uk
what happens if a girl takes viagra viagra online indonesia viagra 100mg usa usa online pharmacies that sell viagra viagra 4 pack
is 5 mg cialis enough dove comprare cialis generico online cialis online us where to buy cialis online review online prescriptions for cialis
how to get a free sample of viagra viagra generico sildenafil mendoza prices for viagra can i take 100mg of viagra super viagra online
walmart viagra price viagra online reviews uk order prescription viagra do online viagra pills work herbal blue viagra
cialis diabetes cialis farmacia online italia order cialis now buy cialis online in canada buy cialis viagra online uk
generic viagra 50 mg uk generico eurofarma do viagra buying viagra online reviews how to take viagra 100mg viagra overnight delivery
viagra and marijuana buy viagra 360 pills viagra for sale online cheap viagra vs generic viagra is generic viagra safe
how long to take viagra before the effect viagra buy online india discount generic viagra generico do viagra em portugal where can i purchase viagra online
viagra levitra online generic viagra by pfizer blue pill viagra can viagra cause depression comprar viagra y cialis generico
cialis in canada online cialis cheap where can i buy cialis online cialis originale online forum buy cialis 30 pills
viagra hard online viagra consultation viagra store usa india generic viagra safe x5 effective viagra
viagra at discount prices get viagra online viagra usa buy viagra online in london silagra vs viagra
what is better viagra or cialis nome generico del viagra buying viagra online reviews what happens when a female takes viagra viagra brand online
viagra online melbourne australia original viagra online australia where can i buy viagra pills generic viagra fda viagra tablets online australia
is viagra prescription only viagra generico in farmacia viagra alternative gnc generic viagra walmart cost dangers of generic viagra
cialis online pharmacy europe female cialis buy cialis sildenafil vs cialis legitimate online pharmacy for cialis
female viagra online viagra generic online usa is viagra generic viagra phone orders how to get viagra prescription online
order cialis by phone cialis 20 cialis 10mg side effects of taking cialis cialis free shipping
effects of cialis on women free cialis pills cialis online canada cialis online singapore cialis order canada
buy viagra cheap online uk trial of viagra best viagra online where to order generic viagra viagra tablets online australia
is it safe to use viagra with high blood pressure viagra online nz online pharmacy viagra can you buy viagra over the counter in the usa buy cheap viagra online canada
kid takes viagra farmacia online viagra paypal buy viagra online canada viagra generic price buy online viagra viagra
viagras best viagra pills viagra cost per pill viagra deals generic viagra capsules
what do viagra pills look like buy herbal viagra online cvs viagra pink pill female viagra viagra online store canada
mail order generic viagra viagra online au generic viagra 100mg picture of viagra tablet sell viagra online legal
generic viagra online overnight delivery online viagra paypal cost of viagra at costco consequences of viagra legitimate viagra online canada
buy cialis once a day cialis online pharmacy cialis 100mg online natural cialis alternatives buy cialis once daily
Do you have a spam problem on this website; I also am a blogger, and I
was wanting to know your situation; many of us have created some nice methods and we
are looking to exchange methods with others, please shoot me an email if interested.
Look into my site – best CBD oil for dogs
order cialis daily cialis warnings side effects of cialis for daily use doses of cialis online apotheke cialis 20mg
pomegranate natural viagra como usar o generico do viagra buy viagra in mexico viagra generico modo de usar viagra online bestellen forum
cheap viagra 50mg cost of generic viagra in india viagra dosage coupon viagra online viagra online chemist
cialis packaging cialis dosage side effects buy cialis for daily use online cialis 360 pills cipla generic cialis
viagra half a pill viagra switzerland online cheap viagra europe what happens if i take 2 viagra best canadian online pharmacy for viagra
buy viagra from pfizer online what is the use of viagra viagra men get viagra sample viagra online overnight delivery
women using viagra online viagra orders cheap viagra sale viagra no prescription us best online generic viagra site
cialis where to buy philippines where to buy cialis forum side effects of cialis cialis headache cure cipla cialis online
alternatives to viagra over the counter how to find viagra pfizer viagra buy viagra online with mastercard buy genuine viagra online canada
cheap generic viagra overnight delivery viagra prices costco buy discount viagra generic viagra cialis online pharmacy viagra and erectile dysfunction
viagra generico dr simi mexico viagra does it make you last longer viagra new york viagra tablet can you take 2 viagra in one day
levitra compared to viagra herbal viagra factory viagra men viagra overnight delivery usa viagra super active generico
viagra safe online order best online viagra pharmacy reviews viagra online uk can you buy viagra without prescription does viagra increase size
cheap viagra in the usa viagra tablets for female can you buy viagra without a prescription generic viagra hong kong buy online viagra tablet
canadian generic viagra online is generic viagra from mexico safe best viagra pills generic viagra sales online what is viagra like
Aw, this was an extremely nice post. Taking the time and actual effort to make a superb article… but what can I say… I procrastinate a
whole lot and don’t manage to get anything done.
Do you have a spam issue on this site; I also am a blogger, and
I was curious about your situation; we have
created some nice methods and we are looking to swap methods with others, be sure to shoot
me an email if interested.
Feel free to visit my web blog: cbd oil for sleep
Hi there, I enjoy reading all of your post. I wanted to write a
little comment to support you.
Hey there! I know this is kinda off topic however I’d figured I’d ask.
Would you be interested in trading links or maybe guest writing a blog
post or vice-versa? My blog addresses a lot of the same subjects as
yours and I feel we could greatly benefit from each other.
If you are interested feel free to shoot me an email.
I look forward to hearing from you! Terrific blog by
the way!
Here is my web-site; CBD for sale
Thanks for the marvelous posting! I seriously enjoyed reading it,
you may be a great author.I will make sure to bookmark your blog and
will eventually come back sometime soon. I want to encourage you continue your great writing, have a nice morning!