PANSTARRS one last time?

This is an awkward time of year for astrophotography. It only gets really dark after the end of “astronomical twilight”, when the Sun dips 18 degrees below the horizon. That didn’t happen until quarter past midnight last night, and by 2am it was back above that 18 degree line. The longest day / shortest night is still six weeks away, so for the next twelve weeks the night sky will be at least as testing as it is now.

These photos were taken in the hour around 1am last night, from the long layby set back from the A591 east of Staveley.

First, the constellation Cepheus:

PANSTARRS approaching Cepheus 50mm f/5.6, ISO 800, 15 min. Single frame of 15 minutes.

PANSTARRS approaching Cepheus
50mm f/5.6, ISO 800, 15 min.
Single frame of 15 minutes.

The 50mm lens gives a 27×18-degree field of view on the D90, so just enough space to accommodate the whole of Cepheus as PANSTARRS (mag 7.2) approaches from Casseopeia.

At ISO 800 all the numbered stars in Cepheus are fully illuminated on the screen, including Erakis (mag 4.1), the “Garnet Star” on the right.

On to PANSTARRS with the 300mm lens:

PANSTARRS approaching Cepheus 300mm f/5.6, ISO 800, 8 min. 2x4 min. frames stacked in Photoshop.

PANSTARRS approaching Cepheus
300mm f/5.6, ISO 800, 8 min.
2×4 min. frames stacked in Photoshop.

PANSTARRS approaching Cepheus 300mm f/5.6, ISO 800, 8 min. Single 8-minute frame.

PANSTARRS approaching Cepheus
300mm f/5.6, ISO 800, 8 min.
Single 8-minute frame.

Two questions are answered here. First, does a stack of two 4-minute frames deliver more than a single 8-minute frame (all other settings unchanged) or is it the other way round? Decide for yourself, but I think there’s more refinement in the layered 4-minute frames and more punch in the single 8-minute frame.

Second, can the EQ3-2 mount track accurately for 8 minutes loaded with the D90 and a 300mm lens? Looks good to me.

At 2am it’s getting light in the east (!!) so time to pack up. I’ve had great fun photographing PANSTARRS over the last few weeks and learned many lessons along the way, but this is probably the last session, given the combination of short, late nights and uncertain Cumbrian weather.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s