203APO 下的愛斯基摩星雲

[社長]

這個NGC2392叫愛斯基摩星雲，因為外形像穿了皮草的愛斯基摩頭像，在中型望遠鏡下也十分光亮及看到一些細節，十分可愛的。

這幅照片僅以203APO接上Canon 5D Mark II，及用了LPS-P2濾鏡，以ISO1600曝光30秒便成，因為表面亮度高，所以在我上水自家天台這種北極星僅見的天空下也可輕易拍到。

因為星雲本身細小，只有0.9x0.9角分，即與木星大小衝日時相若，所以用1420mm焦距拍攝也有點力不從心，而且也很受視寧度影響。

先上張單張中央局部截切，300%出圖，稍後發表疊加圖。

[社長]

稍後發表疊加圖。

[willis]

Maybe one can use DBK21 to image it. I've seen some people use DMK or DBK to do DSI.

[社長]

that's my thought after "process" this, may be I will use DMK41 with Baader RGB filter, that's the same filter and filter wheel I used for Jupiter imaging.

viewtopic.php?f=16&t=43

The Baader RGB filter is perfectly parfocal, and have a nice tranmission gap to cut off light pollution while have max transmission at key spectrum lines, so well suit for deep sky imaging also.

I prefer DMK41 for it's 4.65um (vs 5.6um of 21 series), a bit oversampling may be better for this tiny nebula, so I can use resampling method to process it in Registax.

I spend a hour or so yesterday to run the T-point and now the Paramount polar alignment error is <0.3arcmin, pointing RMS is 61arcsec. So you can imaging the efficiency of this setup - slew to the object by GOTO, and the object is at dead center of the camera, use IC capture of DMK camera and record a short video of may be 30 frame x30sec exposure (max exposure of DMK is 1hr), and then process in registax. Actually I image a few objects with 2hrs this morning.

[David]

This picture very much resembles what I saw in 18"UC. I should save it into my iphone for teaching purpose.

[社長]

wait for a better version from my stacked and process one.

may be the one made with cooled CCD or DMK will be better? I want test how it perform on such small nebula with over-sampling.

[Nebulas]

wait for a better version from my stacked and process one.

may be the one made with cooled CCD or DMK will be better? I want test how it perform on such small nebula with over-sampling.

I suggest to do so. And if shoot the picture with cooled CCD, rather than 5D II, It would appear less noise.

[Nebulas]

這個NGC2392叫愛斯基摩星雲，因為外形像穿了皮草的愛斯基摩頭像，在中型望遠鏡下也十分光亮及看到一些細節，十分可愛的。

這幅照片僅以203APO接上Canon 5D Mark II，及用了LPS-P2濾鏡，以ISO1600曝光30秒便成，因為表面亮度高，所以在我上水自家天台這種北極星僅見的天空下也可輕易拍到。

因為星雲本身細小，只有0.9x0.9角分，即與木星大小衝日時相若，所以用1420mm焦距拍攝也有點力不從心，而且也很受視寧度影響。

先上張單張中央局部截切，300%出圖，稍後發表疊加圖。

期待某天您会选择用1420的焦距的大炮对准Lyra的M57，10年前M57似乎是个和我很熟悉的星云。

能出张照片分享给我就感激不尽了。

[社長]

先來一張今晚用DMK41拍的吧，一時沒想到用Registax處的先天限制，出現了RGB噪點....

[社長]

再來一張昨晚用5D Mark II配LPS-V4拍的，65x30sec @ISO1600，或許要多做些後期處理，或疊加少些，以帶出那些草皮的細節，因為在個別幀中是看到的。

照片中央裁切，300%出圖，沒平場沒暗場。

[David]

You may want to try to shoot "Ghost of Jupiter" in Hydra (NGC3242) when the time is right. Its apparent size is rouhgly the same as jupiter at opposition and has a few layers of gas shells like the Eskimo.