procedure tcombine (nScans,impref1,impref2,impref3,start1,end1,start2,end2, start3,end3,inExtn,outType,clnNum,clnOver,clnExtn,clipmode,gnW,rnW,sumNum, sumOver,sumExtn,outpref,maskType,maskZer,clnmaRMS,summaRMS,logname,convFits)

int nScans	{3,prompt="Number of image scans (<=3)"}
string impref1 	{prompt="    Scan 1: Image name prefix"}
string impref2 	{prompt="    Scan 2: Image name prefix"}
string impref3 	{prompt="    Scan 3: Image name prefix"}
int start1	{prompt="    Scan 1: Image start number"}
int end1	{prompt="    Scan 1: Image finish number"}
int start2	{prompt="    Scan 2: Image start number"}
int end2	{prompt="    Scan 2: Image finish number"}
int start3	{prompt="    Scan 3: Image start number"}
int end3	{prompt="    Scan 3: Image finish number"}
string inExtn   {"r", prompt="Extension for all input images?"}
string outType	{"cleaned", prompt="Output images (cleaned|summed|both)"}
int clnNum	{2, prompt="    Cleaned: 2 or 1 combined images output slice"}
bool clnOver	{yes, prompt="    Cleaned: Overlap adjacent images?"}
string clnExtn  {"c1", prompt="    Cleaned: Output image extension?"}
string clipmode	{"avsigclip", prompt="    Cleaning method (avsigclip|pclip|crreject)"}
real gnW	{2.74, prompt="  -> crreject: CCD gain (e-/ADU)"}
real rnW	{4.8, prompt="  -> crreject: CCD read noise (e-)"}
int sumNum	{2, prompt="    Summed: 2 or 1 combined images per slice"}
bool sumOver	{no, prompt="    Summed: Overlap adjacent images?"}
string sumExtn  {"s1", prompt="    Summed: Output image extension?"}
string outpref	{"b", prompt="Prefix for all output images?"}
string maskType	{"rms", prompt="Apply corner mask? (none|zero|rms)"}
string maskZer	{"-",prompt="     Zero mask image (full name)"}
string clnmaRMS	{"--",prompt="     Cleaned: RMS mask image (full name)"}
string summaRMS	{"---",prompt="     Summed: RMS mask image (full name)"}
string logname	{"STDOUT", prompt="Log file written here"}
bool convFits	{no, prompt="Convert output images to FITS FORMAT?"}
struct *flist1a		# list-directed structure to go thru scan 1
struct *flist1b		# list-directed structure to go thru scan 1
struct *flist2a		# list-directed structure to go thru scan 2
struct *flist2b		# list-directed structure to go thru scan 2
struct *flist3a		# list-directed structure to go thru scan 3
struct *flist3b		# list-directed structure to go thru scan 3





begin


	# Variable Declarations:
	struct image1b		# 2nd image from list 1 (if combining in pairs)
				# or 1st image (if combining individually)
	struct image1a		# 1st image from list 1 (if combining in pairs)
	struct image2b
	struct image2a	 
	struct image3b	
	struct image3a
	string itemp		# temporary image name; not used for anything
	string outIm		# name of output image
	string fitsname		# name of fits version of image



	if (! defpac ("images")) {
		print("Package IMAGES needs to be loaded.")
		bye
	}





	# Cleaning-up old files and ones about to be created:
	delete (files="temp_tcomb*",go_ahea+,ver-)
	imdelete (images="tempImg",verify=no,default=yes, go_ahead=yes)



	# Creating individual scan lists:
	#	temp_tcomb1	- 1st scan
	#	temp_tcomb2	- 2nd scan
	#	temp_tcomb3	- 3rd scan
	#	temp_tcomb4	- all scans concatenated

	print (" ")
	print ("Creating image lists (please wait) ...")
	print (" ")
	if ((nScans>=1)&&(nScans<=3)) {
	tmakefile (file_out="temp_tcomb1",startNum=start1,stopNum=end1, prefixOU=impref1,anyExtn-,extnOU="",padOU+,listImgs-)
	!cp temp_tcomb1 temp_tcomb4
	}
	if ((nScans>=2)&&(nScans<=3)) {
	tmakefile (file_out="temp_tcomb2",startNum=start2,stopNum=end2, prefixOU=impref2,anyExtn-,extnOU="",padOU+,listImgs-)
	! cat -s temp_tcomb4 temp_tcomb2 >> temp_tcomb4
	}
	if (nScans==3) {
	tmakefile (file_out="temp_tcomb3",startNum=start3,stopNum=end3, prefixOU=impref3,anyExtn-,extnOU="",padOU+,listImgs-)
	! cat -s temp_tcomb4 temp_tcomb3 >> temp_tcomb4
	}
	if (nScans>3) {
		print ("  ")
		print (" *** Invalid number of scans *** ")
		bye
	}
	if (nScans<1) {
		print ("  ")
		print (" *** Invalid number of scans *** ")
		bye
	}





	# CLEANED ----------------------------------------------------------

	if ((outType=="cleaned")||(outType=="both")) {

	if ((clnNum==1)&&(clnOver==yes)) {		
		print ("  ")
		print (" *** Can not overlap single-slice CLEANED output *** ")
		print (" --> resetting clnOver to no")
		print (" ")
		clnOver=no
	}


	print (" ")
	print ("============================================================")
	print (" ")
	print ("Creating CLEANED images ...")
	print (" ")
	print ("Input slices per output slice: "//clnNum)
	if (clnOver==yes) {
		print ("Overlapping slices: Yes")
	}
	if (clnOver==no) {
		print ("Overlapping slices: No")
	}
	print (" ")

	# Initialising scan position of the second image scan variable
	# (or first image scan variable in the case of individual combination)
	if ((nScans>=1)&&(nScans<=3)) {
		flist1a = "temp_tcomb1"
		flist1b = "temp_tcomb1"
		itemp = fscan(flist1b, image1b)
		# delete(files="temp_tcomb.jnk",verify-,default+,go_ahead+)
		print(image1b//inExtn, > "temp_tcomb.jnk")
	}
	if ((nScans>=2)&&(nScans<=3)) {
		flist2a = "temp_tcomb2"
		flist2b = "temp_tcomb2"		
		itemp = fscan(flist2b, image2b)
		print(image2b//inExtn, >> "temp_tcomb.jnk")
	}
	if (nScans==3) {
		flist3a = "temp_tcomb3"
		flist3b = "temp_tcomb3"		
		itemp = fscan(flist3b, image3b)
		print(image3b//inExtn, >> "temp_tcomb.jnk")
	}

	if (clnNum==1) {
		outIm = image1b//clnExtn
		imdelete (images=outIm,verify=no,default=yes, go_ahead=yes)
		# type (input_fi="temp_tcomb.jnk")
		# print (" --> combined to make image: "//outIm)
		# print ("--------------------------------------")
		# print (" ")

	if ((clipmode=="avsigclip")||(clipmode=="pclip")) {
imcombine(inp="@temp_tcomb.jnk",output=outIm,logfile=logname,combine="median", rej=clipmode,proj=no,outty="real",offse="none",maskty="none",scale="none", zer="none",weig="none",statsec="",lthr=INDEF,hthr=INDEF,nkee=0, mclip=yes,lsig=2.5,hsig=2.5)
	} else {
imcombine(inp="@temp_tcomb.jnk",output=outIm,logfile=logname,combine="median", rej="crreject",proj=no,outty="real",offse="none",maskty="none",scale="none", zer="none",weig="none",statsec="",lthr=INDEF,hthr=INDEF,nkee=0, mclip=no,lsig=2.5,hsig=2.5, rdnoise=rnW, gain=gnW, snoise=0.)
	# i.e. differs in the rej and mclip parameters mainly	
	}



		if ((maskType=="zero")||(maskType=="rms")) {

		# Multiplying by zero mask (required by both cases):
		imarith(operand1=outIm,op="*",operand2=maskZer, result="tempImg",title="combined image",divzero=0,verb=no)
		imdelete (images=outIm,verify=no,default=yes, go_ahead=yes)
		imrename (oldnames="tempImg",newnames=outIm,verb=no)

		if (maskType=="rms") {
		       # Adding RMS mask:
		       imarith(operand1=outIm,op="+",operand2=clnmaRMS, result="tempImg",title="combined image",divzero=0,verb=no)
		       imdelete (images=outIm,verify-,default+, go_ahead+)
		       imrename (oldnames="tempImg",newnames=outIm,verb-)
		}
		}



		if (convFits==yes) {
		fitsname = outIm//".fits"
		print (" ")
		print (" Converting "//outIm//" to fits ("//fitsname//") ...")
		imdelete (images=fitsname,verify=no,default=yes, go_ahead=yes)
		imrename (oldnames=outIm,newnames="tempImg",verb=no)
		wfits(iraf_fil="tempImg",fits_fil=fitsname, make_im+,long_he-, short_h+,bitpix=0,blockin=0,scale+,autosca+, bscale=1.,bzero=0.)
		imdelete (images="tempImg",verify=no,default=yes, go_ahead=yes)
		}


	}

	# Main CLEANED loop:
	while ( fscan(flist1b, image1b) != EOF) {


		if (clnNum==2) {
		delete(files="temp_tcomb.jnk",verify-,default+,go_ahead+)

			if ((nScans>=1)&&(nScans<=3)) {
			itemp = fscan(flist1a, image1a)
			print(image1a//inExtn, > "temp_tcomb.jnk")
			}
			if ((nScans>=2)&&(nScans<=3)) {
			itemp = fscan(flist2a, image2a)
			print(image2a//inExtn, >> "temp_tcomb.jnk")
			}
			if (nScans==3) {
			itemp = fscan(flist3a, image3a)
			print(image3a//inExtn, >> "temp_tcomb.jnk")
			}
		}
		# i.e. only obtain previous images if combining in pairs


		# Writing the image defining this main loop (2 cases depending
		# on whether the above routine was used or bypassed):
		if (clnNum==1) {
		delete(files="temp_tcomb.jnk",verify-,default+,go_ahead+)
		print(image1b//inExtn, > "temp_tcomb.jnk")
		outIm = image1b//clnExtn
		}
		if (clnNum==2) {
		print(image1b//inExtn, >> "temp_tcomb.jnk")
		outIm = image1a//clnExtn
		}


		# scanning other images accordingly (if additional scans exist):
		if ((nScans>=2)&&(nScans<=3)) {
		itemp = fscan(flist2b, image2b)
		print(image2b//inExtn, >> "temp_tcomb.jnk")
		}
		if (nScans==3) {
		itemp = fscan(flist3b, image3b)
		print(image3b//inExtn, >> "temp_tcomb.jnk")
		}


		imdelete (images=outIm,verify=no,default=yes, go_ahead=yes)
		# type (input_fi="temp_tcomb.jnk")
		# print (" --> combined to make image: "//outIm)
		# print ("--------------------------------------")
		# print (" ")

		if ((clnNum==2)&&(clnOver==no)) {
			if ((nScans>=1)&&(nScans<=3)) {
			itemp = fscan(flist1a, image1a)
			itemp = fscan(flist1b, image1b)
			}
			if ((nScans>=2)&&(nScans<=3)) {
			itemp = fscan(flist2a, image2a)
			itemp = fscan(flist2b, image2b)
			}
			if (nScans==3) {
			itemp = fscan(flist3a, image3a)
			itemp = fscan(flist3b, image3b)
			}
		}
		# extra bit of scanning forward for non-overlap of pairs

			
	if ((clipmode=="avsigclip")||(clipmode=="pclip")) {
imcombine(inp="@temp_tcomb.jnk",output=outIm,logfile=logname,combine="median", rej=clipmode,proj=no,outty="real",offse="none",maskty="none",scale="none", zer="none",weig="none",statsec="",lthr=INDEF,hthr=INDEF,nkee=0, mclip=yes,lsig=2.5,hsig=2.5)
	} else {
imcombine(inp="@temp_tcomb.jnk",output=outIm,logfile=logname,combine="median", rej=clipmode,proj=no,outty="real",offse="none",maskty="none",scale="none", zer="none",weig="none",statsec="",lthr=INDEF,hthr=INDEF,nkee=0, mclip=no,lsig=2.5,hsig=2.5, rdnoise=rnW, gain=gnW, snoise=0.)
	# i.e. differs in the rej and mclip parameters mainly
	}

		if ((maskType=="zero")||(maskType=="rms")) {

		# Multiplying by zero mask (required by both cases):
		imarith(operand1=outIm,op="*",operand2=maskZer, result="tempImg",title="combined image",divzero=0,verb=no)
		imdelete (images=outIm,verify=no,default=yes, go_ahead=yes)
		imrename (oldnames="tempImg",newnames=outIm,verb=no)

		if (maskType=="rms") {
		       # Adding RMS mask:
		       imarith(operand1=outIm,op="+",operand2=clnmaRMS, result="tempImg",title="combined image",divzero=0,verb=no)
		       imdelete (images=outIm,verify-,default+, go_ahead+)
		       imrename (oldnames="tempImg",newnames=outIm,verb-)
		}
		}


		if (convFits==yes) {
		fitsname = outIm//".fits"
		print (" ")
		print (" Converting "//outIm//" to fits ("//fitsname//") ...")
		imdelete (images=fitsname,verify=no,default=yes, go_ahead=yes)
		imrename (oldnames=outIm,newnames="tempImg",verb=no)
		wfits(iraf_fil="tempImg",fits_fil=fitsname, make_im+,long_he-, short_h+,bitpix=0,blockin=0,scale+,autosca+, bscale=1.,bzero=0.)
		imdelete (images="tempImg",verify=no,default=yes, go_ahead=yes)
		}


	}


	}
	# end of CLEANED ---------------------------------------------------


	delete (files="temp_tcomb.jnk",go_ahea+,ver-)



	# SUMMED -----------------------------------------------------------

	if ((outType=="summed")||(outType=="both")) {

	if ((sumNum==1)&&(sumOver==yes)) {		
		print ("  ")
		print (" *** Can not overlap single-slice SUMMED output *** ")
		print (" --> resetting sumOver to no")
		print (" ")
		clnOver=no
	}


	print (" ")
	print ("============================================================")
	print (" ")
	print ("Creating SUMMED images ...")
	print (" ")
	print ("Input slices per output slice: "//sumNum)
	if (sumOver==yes) {
		print ("Overlapping slices: Yes")
	}
	if (sumOver==no) {
		print ("Overlapping slices: No")
	}
	print (" ")

	# Initialising scan position of the second image scan variable
	# (or first image scan variable in the case of individual combination)
	if ((nScans>=1)&&(nScans<=3)) {
		flist1a = "temp_tcomb1"
		flist1b = "temp_tcomb1"
		itemp = fscan(flist1b, image1b)
		# delete(files="temp_tcomb.jnk",verify-,default+,go_ahead+)
		print(image1b//inExtn, > "temp_tcomb.jnk")
	}
	if ((nScans>=2)&&(nScans<=3)) {
		flist2a = "temp_tcomb2"
		flist2b = "temp_tcomb2"		
		itemp = fscan(flist2b, image2b)
		print(image2b//inExtn, >> "temp_tcomb.jnk")
	}
	if (nScans==3) {
		flist3a = "temp_tcomb3"
		flist3b = "temp_tcomb3"		
		itemp = fscan(flist3b, image3b)
		print(image3b//inExtn, >> "temp_tcomb.jnk")
	}

	if (sumNum==1) {
		outIm = image1b//sumExtn
		imdelete (images=outIm,verify=no,default=yes, go_ahead=yes)
		# type (input_fi="temp_tcomb.jnk")
		# print (" --> summed to make image: "//outIm)
		# print ("--------------------------------------")
		# print (" ")

imsum(inp="@temp_tcomb.jnk",output=outIm,title="summed image",option="sum",low_rej=0., high_rej=0.,verb+)



		if ((maskType=="zero")||(maskType=="rms")) {

		# Multiplying by zero mask (required by both cases):
		imarith(operand1=outIm,op="*",operand2=maskZer, result="tempImg",title="combined image",divzero=0,verb=no)
		imdelete (images=outIm,verify=no,default=yes, go_ahead=yes)
		imrename (oldnames="tempImg",newnames=outIm,verb=no)

		if (maskType=="rms") {
		       # Adding RMS mask:
		       imarith(operand1=outIm,op="+",operand2=summaRMS, result="tempImg",title="combined image",divzero=0,verb=no)
		       imdelete (images=outIm,verify-,default+, go_ahead+)
		       imrename (oldnames="tempImg",newnames=outIm,verb-)
		}
		}



		if (convFits==yes) {
		fitsname = outIm//".fits"
		print (" ")
		print (" Converting "//outIm//" to fits ("//fitsname//") ...")
		imdelete (images=fitsname,verify=no,default=yes, go_ahead=yes)
		imrename (oldnames=outIm,newnames="tempImg",verb=no)
		wfits(iraf_fil="tempImg",fits_fil=fitsname, make_im+,long_he-, short_h+,bitpix=0,blockin=0,scale+,autosca+, bscale=1.,bzero=0.)
		imdelete (images="tempImg",verify=no,default=yes, go_ahead=yes)
		}

	}

	# Main SUMMED loop:
	while ( fscan(flist1b, image1b) != EOF) {


		if (sumNum==2) {
		delete(files="temp_tcomb.jnk",verify-,default+,go_ahead+)

			if ((nScans>=1)&&(nScans<=3)) {
			itemp = fscan(flist1a, image1a)
			print(image1a//inExtn, > "temp_tcomb.jnk")
			}
			if ((nScans>=2)&&(nScans<=3)) {
			itemp = fscan(flist2a, image2a)
			print(image2a//inExtn, >> "temp_tcomb.jnk")
			}
			if (nScans==3) {
			itemp = fscan(flist3a, image3a)
			print(image3a//inExtn, >> "temp_tcomb.jnk")
			}
		}
		# i.e. only obtain previous images if combining in pairs


		# Writing the image defining this main loop (2 cases depending
		# on whether the above routine was used or bypassed):
		if (sumNum==1) {
		delete(files="temp_tcomb.jnk",verify-,default+,go_ahead+)
		print(image1b//inExtn, > "temp_tcomb.jnk")
		outIm = image1b//sumExtn
		}
		if (sumNum==2) {
		print(image1b//inExtn, >> "temp_tcomb.jnk")
		outIm = image1a//sumExtn
		}


		# scanning other images accordingly (if additional scans exist):
		if ((nScans>=2)&&(nScans<=3)) {
		itemp = fscan(flist2b, image2b)
		print(image2b//inExtn, >> "temp_tcomb.jnk")
		}
		if (nScans==3) {
		itemp = fscan(flist3b, image3b)
		print(image3b//inExtn, >> "temp_tcomb.jnk")
		}


		imdelete (images=outIm,verify=no,default=yes, go_ahead=yes)
		# type (input_fi="temp_tcomb.jnk")
		# print (" --> summed to make image: "//outIm)
		# print ("--------------------------------------")
		# print (" ")

		if ((sumNum==2)&&(sumOver==no)) {
			if ((nScans>=1)&&(nScans<=3)) {
			itemp = fscan(flist1a, image1a)
			itemp = fscan(flist1b, image1b)
			}
			if ((nScans>=2)&&(nScans<=3)) {
			itemp = fscan(flist2a, image2a)
			itemp = fscan(flist2b, image2b)
			}
			if (nScans==3) {
			itemp = fscan(flist3a, image3a)
			itemp = fscan(flist3b, image3b)
			}
		}
		# extra bit of scanning forward for non-overlap of pairs

			

imsum(inp="@temp_tcomb.jnk",output=outIm,title="summed image",option="sum",low_rej=0., high_rej=0.,verb+)



		if ((maskType=="zero")||(maskType=="rms")) {

		# Multiplying by zero mask (required by both cases):
		imarith(operand1=outIm,op="*",operand2=maskZer, result="tempImg",title="combined image",divzero=0,verb=no)
		imdelete (images=outIm,verify=no,default=yes, go_ahead=yes)
		imrename (oldnames="tempImg",newnames=outIm,verb=no)

		if (maskType=="rms") {
		       # Adding RMS mask:
		       imarith(operand1=outIm,op="+",operand2=summaRMS, result="tempImg",title="combined image",divzero=0,verb=no)
		       imdelete (images=outIm,verify-,default+, go_ahead+)
		       imrename (oldnames="tempImg",newnames=outIm,verb-)
		}
		}



		if (convFits==yes) {
		fitsname = outIm//".fits"
		print (" ")
		print (" Converting "//outIm//" to fits ("//fitsname//") ...")
		imdelete (images=fitsname,verify=no,default=yes, go_ahead=yes)
		imrename (oldnames=outIm,newnames="tempImg",verb=no)
		wfits(iraf_fil="tempImg",fits_fil=fitsname, make_im+,long_he-, short_h+,bitpix=0,blockin=0,scale+,autosca+, bscale=1.,bzero=0.)
		imdelete (images="tempImg",verify=no,default=yes, go_ahead=yes)
		}

	}


	}
	# end of SUMMED ---------------------------------------------------



	delete (files="temp_tcomb*",go_ahea+,ver-)

	print (" ")
	print ("============================================================")
	print (" ")
	print (" ")
	print ("Done.")
	print (" ")

end