swarp failing to run on image mosaicked using swarp

[shruti-ramaiya]

Hi!

I'm using swarp for a two step process:

1. mosaicking together three image tiles of an astronomical field to form one image
2. regridding/resampling other images onto the same pixel scale as my mosaicked image

The first step worked perfectly (or so I think anyway!) and produced a mosaic that, upon looking at, seems correct. I used the following parameter file for this:

`# Default configuration file for SWarp 2.41.5

EB 2024-11-28

#----------------------------------- Output -----------------------------------
IMAGEOUT_NAME coadd.fits # Output filename
WEIGHTOUT_NAME coadd.weight.fits # Output weight-map filename

HEADER_ONLY N # Only a header as an output file (Y/N)?
HEADER_SUFFIX .head # Filename extension for additional headers

#------------------------------- Input Weights --------------------------------

WEIGHT_TYPE MAP_WEIGHT # BACKGROUND,MAP_RMS,MAP_VARIANCE
# or MAP_WEIGHT
##WEIGHT_SUFFIX # Suffix to use for weight-maps
WEIGHT_IMAGE /mnt/hoy/VIDEO_FINAL/xmm1_Ks_conf.fits,/mnt/hoy/VIDEO_FINAL/xmm2_Ks_conf.fits,/mnt/hoy/VIDEO_FINAL/xmm3_Ks_conf.fits # Weightmap filename if suffix not used
# (all or for each weight-map)

#------------------------------- Co-addition ----------------------------------

COMBINE Y # Combine resampled images (Y/N)?
COMBINE_TYPE WEIGHTED # MEDIAN,AVERAGE,MIN,MAX,WEIGHTED,CLIPPED
# CHI-OLD,CHI-MODE,CHI-MEAN,SUM,
# WEIGHTED_WEIGHT,MEDIAN_WEIGHT,
# AND,NAND,OR or NOR

#-------------------------------- Astrometry ----------------------------------

CELESTIAL_TYPE NATIVE # NATIVE, PIXEL, EQUATORIAL,
# GALACTIC,ECLIPTIC, or SUPERGALACTIC
PROJECTION_TYPE TAN # Any WCS projection code or NONE
PROJECTION_ERR 0.001 # Maximum projection error (in output
# pixels), or 0 for no approximation
CENTER_TYPE ALL # MANUAL, ALL or MOST
CENTER 00:00:00.0, +00:00:00.0 # Coordinates of the image center
PIXELSCALE_TYPE MEDIAN # MANUAL,FIT,MIN,MAX or MEDIAN
PIXEL_SCALE 0.0 # Pixel scale
IMAGE_SIZE 0 # Image size (0 = AUTOMATIC)

#-------------------------------- Resampling ----------------------------------

RESAMPLE Y # Resample input images (Y/N)?
RESAMPLE_DIR . # Directory path for resampled images
RESAMPLE_SUFFIX .resamp.fits # filename extension for resampled images

RESAMPLING_TYPE LANCZOS3 # NEAREST,BILINEAR,LANCZOS2,LANCZOS3
# LANCZOS4 (1 per axis) or FLAGS
OVERSAMPLING 0 # Oversampling in each dimension
# (0 = automatic)
INTERPOLATE N # Interpolate bad input pixels (Y/N)?
# (all or for each image)

FSCALASTRO_TYPE FIXED # NONE,FIXED, or VARIABLE
FSCALE_KEYWORD FLXSCALE # FITS keyword for the multiplicative
# factor applied to each input image
FSCALE_DEFAULT 1.0 # Default FSCALE value if not in header

GAIN_KEYWORD GAIN # FITS keyword for effect. gain (e-/ADU)
GAIN_DEFAULT 0.0 # Default gain if no FITS keyword found

#--------------------------- Background subtraction ---------------------------

SUBTRACT_BACK N # Subtraction sky background (Y/N)?
# (all or for each image)

BACK_TYPE AUTO # AUTO or MANUAL
# (all or for each image)
BACK_DEFAULT 0.0 # Default background value in MANUAL
# (all or for each image)
BACK_SIZE 128 # Background mesh size (pixels)
# (all or for each image)
BACK_FILTERSIZE 3 # Background map filter range (meshes)
# (all or for each image)

#------------------------------ Memory management -----------------------------

VMEM_DIR . # Directory path for swap files
VMEM_MAX 16384 # Maximum amount of virtual memory (MB)
MEM_MAX 2048 # Maximum amount of usable RAM (MB)
COMBINE_BUFSIZE 2048 # RAM dedicated to co-addition(MB)

#------------------------------ Miscellaneous ---------------------------------

DELETE_TMPFILES Y # Delete temporary resampled FITS files
# (Y/N)?
COPY_KEYWORDS OBJECT # List of FITS keywords to propagate
# from the input to the output headers
WRITE_FILEINFO N # Write information about each input
# file in the output image header?
WRITE_XML Y # Write XML file (Y/N)?
XML_NAME swarp.xml # Filename for XML output
VERBOSE_TYPE NORMAL # QUIET,LOG,NORMAL, or FULL

NTHREADS 0 # Number of simultaneous threads for
# the SMP version of SWarp
# 0 = automatic`

now, when going to regrid other images onto the pixel scale of the mosaicked image that I get from step 1, I get the following error:

Error while reading /mnt/users/ramaiyas/image_swarping/mosaics/vistaKs_results/cdfs_mosaic_vistaKs.fits

it seems only to be an issue when running swarp on mosaicked images but im unsure why this would be - I have checked the header and all seems normal/correct. I was wondering if anyone had any insights into this - any help would be most appreciated!

thank you!