Iris is astronomer's software also and I've been tinkering with it, trying to figure out how to convert RAW camera files. I'll summarize what I've been able to make of it. Most of the tutorial info on their web site is geared toward processing multiple exposures of the same scene for astronomy stuff and will make no sense to a regular photographer.

http://astrosurf.com/buil/us/iris/iris.htm

Click the camera icon in the toolbar to set your camera model before loading. Select linear (think this makes the image appear too dark but gives a good objective view of the data). You can set the WB on this dialogue box with RGB values but I have no idea how to determine the right numbers.

File menu > Settings to set the 'Working Path' where files will be saved out to & opened from.

File > Load Raw brings up the RAW file in grainy B&W bayer pattern grey scale, zoom in to see the RGB pattern in grey. The zoom tools on the toolbar are blue icons.

The Threshold dialogue should be visible, set the top box to 4095 & the bottom to 0. For astronomy work, you can figure out a dark frame subtraction (shot with the lens cap on) to set the blackpoint higher than zero in some cases such as a Canon 20D has the blackpoint at 128 allowing some room for analyzing background noise. You can fiddle with the threshold sliders for the proper look of brightness & contrast but when doing an analysis of raw values, don't worry if it looks dark, that's the linear conversion. This is not in any specific color space (ie sRGB) just raw sensor data. See below for adjusting gamma.

Applying the threshold sliders causes clipping so it's an interesting way to examine the data in a given range but isn't the same as applying a curve, it's just enlarging a slice of the dynamic range.

Wave the cursor around & in the lower right status bar you see the raw values from 0-4095 so you can see here if there is anything at all to be recovered in highlights & shadows. I think you can split the image into RG&B files to see which channel is blown or not. This is all before the whole thing gets muddied up by merging the bayer pattern RGB.

You can use the binning option in the Geometry menu with a value of 2 to merge into a halfsize greyscale image which ought to reduce random noise better than starting with a regular conversion.

Note: if you want to equalize the histogram and make it closer to a normal s-curve instead of linear, logarithm and equalization operations need to be done on the initial bay pattern raw file before doing CFA (below). The tutorials talk about a DDP = Digital Development Process but I don't see that on the menu. If you apply gamma or equalization after CFA it has no impact on the TIF when opened in PS, all the data is still crammed over in the far left of the histogram. I can adjust levels in PS but it posterizes severely & the whole point is to expand into the desired range before chopping 4095 down to 255.

From the Digital Photo menu select 'Convert a CFA image' to interpolate the RGB bayer pattern into a normal color image. It probably looks too green because it needs to be white balanced. From the Digital Photo menu select 'RGB Balance' if you want to try... no undo that I can see so it's frustrating. Alternatively use the View menu > White balance, it seems the same. Also in the View menu is Gamma Adjustment, I found that around 3 or 4 begins to look like a normal exposure, I don't know if this is equivalent to actually taking out the linear data structure and the median or gradient settings on the camera menu are not much different.

From there just save as a tif & when opening in photoshop, sRGB seems as good as any color space to assign. Then I do a levels adjustment to set the brightness & gamma level to make it look like a normal exposure.

You can search the web site for terms like 'binning' with the following format:
site:astrosurf.com/buil/us/iris binning