WFPC2 Instrument Handbook for Cycle 11

Red Leaks in UV Filters

---

The "red leaks" in the UV filters are shown in Figure 3.10 for F122M, F160BW (the new Wood's filter), F170W, F185W, F218W F255W, F300W, and F336W. The presence of significant red leaks in the UV filters, together with the much greater sensitivity and wavelength coverage in the red part of the spectrum, makes calibration of UV observations difficult. Table 3.13 shows red leak estimates as a percentage of the total detected flux from de-reddened stellar sources, ordered by spectral type. In each column, the red leak is defined as the percentage of the detected flux longward of the cutoff wavelength in the third row. In the presence of interstellar reddening, the red leaks will be larger.

Figure 3.10: UV Filter Red Leaks. Includes the on-orbit measurements of system response.  
 

Table 3.13: Red Leak in UV Filters. A synthetic photometry calculation with de-reddened BPGS stellar spectra and system response from on-orbit data.

Filter Central (nm) Cutoff (nm)		F122M 122 140	F160BW 160 240	F170W 170 260	F185W 185 260	F218W 218 280	F255W 255 310	F300W 300 400	F336W 336 400	F122M 122 380	F160BW 160 380	F170W 170 380	F185W 185 380	F218W 218 380	F255W| 255 380	F300W 300 380	F336W 336 380
9 SGR	O5	16.9		0.7	0.4	0.2	0.3		0.1	0.3		0.1				0.5	0.1
9 SGE	O8F	16.9		0.7	0.4	0.2	0.3		0.1	0.3		0.1				0.5	0.1
HR 8D23	O6	21.8		1.0	0.5	0.3	0.4		0.1	0.6		0.1				0.6	0.1
-1935	B1V	20.1		0.8	0.4	0.3	0.4		0.1	0.6		0.1				0.6	0.2
60 CYG	B1V	20.1		0.8	0.4	0.3	0.4		0.1	0.6		0.1				0.6	0.2
102 HER	B2V	22.5		1.2	0.6	0.4	0.4	0.1	0.1	1.1		0.2	0.1			0.8	0.2
ETA HYA	B3V	22.7		1.2	0.6	0.4	0.5	0.1	0.1	1.3		0.3	0.1			0.9	0.2
IOTA HER	B3V	22.7		1.2	0.6	0.4	0.5	0.1	0.2	1.3		0.3	0.1			0.9	0.2
HR 7899	B4V	22.7		1.2	0.6	0.4	0.5	0.1	0.2	1.4		0.3	0.1			0.9	0.2
38 OPH	A1V	30.0		1.6	0.7	0.5	0.5	0.1	0.2	2.9		0.5	0.1			1.1	0.3
HR 7174	B6V	30.7		1.8	0.8	0.5	0.5	0.1	0.3	3.8		0.7	0.2		0.1	1.3	0.4
9 VUL	B7V	30.8		1.8	0.8	0.5	0.5	0.1	0.3	3.9		0.7	0.2		0.1	1.4	0.4
HD 189689	B9V	41.1		2.4	0.9	0.5	0.6	0.2	0.3	7.4		1.0	0.2		0.1	1.6	0.4
THETA VIR	A0V	59.6		4.0	1.2	0.6	0.8	0.3	0.6	20.3		2.2	0.4	0.1	0.1	2.5	0.7
NU CAP	B9V	58.6		3.7	1.2	0.6	0.8	0.3	0.5	18.3		2.0	0.4	0.1	0.1	2.2	0.6
HR 6169	A2V	59.5		4.0	1.2	0.6	0.8	0.3	0.6	20.1		2.2	0.4	0.1	0.1	2.3	0.7
HD 140849A	A1V	73.7		3.8	1.1	0.6	0.7	0.3	0.5	23.7		2.0	0.4	0.1	0.1	2.0	0.6
69 HER	A2V	59.5		3.9	1.2	0.6	0.8	0.3	0.6	20.0		2.2	0.4	0.1	0.1	2.2	0.7
HD 140849B	A3V	89.0		6.5	1.5	0.8	1.0	0.4	0.6	44.0		3.9	0.6	0.1	0.2	2.4	0.7
58 AQL	A0V	75.5		4.3	1.3	0.6	0.8	0.3	0.7	28.6		2.5	0.5	0.1	0.1	2.7	0.8
78 HER	B9V	75.0		4.2	1.2	0.6	0.7	0.3	0.7	27.5		2.4	0.5	0.1	0.1	2.4	0.8
HR 6570	A7V	89.7		7.0	1.6	0.8	1.0	0.4	0.7	47.6		4.4	0.7	0.1	0.2	2.6	0.9
HD 187754	A2V	97.9		11.0	2.1	0.9	1.2	0.5	0.9	64.4		7.4	1.0	0.2	0.2	3.2	1.1
THETA 1 SER	A5V	97.7		9.8	1.9	0.9	1.1	0.4	0.8	60.3		6.2	0.8	0.1	0.2	2.6	0.9
PRAESEPE 276		99.7		12.1	2.2	1.0	1.2	0.5	0.9	67.5		8.1	1.1	0.2	0.2	2.9	1.0
PRAESEPE 114		99.7		11.6	2.2	1.0	1.2	0.5	0.9	66.0		7.6	1.0	0.2	0.2	2.7	1.0
PRAESEPE 154		100.0		17.0	3.0	1.1	1.3	0.5	0.9	71.9		11.4	1.4	0.2	0.2	2.8	1.0
HD 140192	A5V	100.0		17.4	3.0	1.1	1.3	0.6	0.9	72.7		11.7	1.5	0.2	0.2	2.9	1.1
PRAESEPE 226		100.0		17.2	3.0	1.1	1.3	0.6	1.0	72.7		11.6	1.4	0.2	0.2	2.7	1.1
PRAESEPE 37		100.0		38.8	7.7	2.0	1.7	0.6	1.0	80.8		27.0	3.9	0.3	0.3	2.8	1.1
HD 191177	F4V	100.0		64.9	17.6	3.0	2.3	0.8	1.1	86.1		48.4	10.1	0.6	0.5	3.6	1.3
PRAESEPE 332		100.0		62.4	16.3	2.9	2.2	0.7	1.0	84.6		44.9	8.8	0.5	0.4	2.9	1.1
BD+293891	F6V	100.0		67.4	19.4	3.7	2.5	0.8	1.1	86.4		49.8	11.0	0.7	0.4	3.1	1.2
PRAESEPE 222		100.0		50.7	11.4	2.8	2.2	0.8	1.1	84.7		36.8	6.2	0.5	0.4	2.8	1.2
HD 35246	F8V	100.0		52.1	11.8	2.9	2.2	0.8	1.3	85.8		38.6	6.6	0.5	0.4	2.8	1.4
BD+263780	G0V	100.0		52.4	11.9	2.9	2.2	0.9	1.3	86.0		38.9	6.7	0.5	0.4	2.8	1.4
HD 148816	F9V	100.0		51.1	11.5	2.8	2.2	0.8	1.2	85.0		37.2	6.3	0.5	0.3	2.8	1.3
HD 155675	F8V	100.0		69.0	20.5	4.7	3.4	1.0	1.3	88.7		53.3	12.4	0.9	0.6	3.3	1.4
PRAESEPE 418		100.0		70.2	21.1	4.8	3.5	1.0	1.4	89.4		55.0	13.2	1.0	0.6	3.2	1.5
HYAD 1		100.0		71.4	21.9	4.8	3.5	1.1	1.5	90.0		56.8	14.1	1.0	0.6	3.4	1.6
HD 122693	F8V	100.0		71.6	22.1	4.9	3.5	1.1	1.6	90.1		57.1	14.2	1.1	0.6	3.5	1.7
HD 154417	F8V	100.0		70.6	21.4	4.8	3.5	1.1	1.4	89.5		55.5	13.4	1.0	0.6	3.2	1.5
HYAD 2		100.0		89.2	46.7	7.9	3.4	1.2	1.6	91.2		71.6	30.3	1.7	0.6	3.3	1.7
HD 227547	G5V	100.0		89.5	47.2	8.0	3.4	1.2	1.7	91.4		72.0	30.7	1.7	0.6	3.3	1.8
HD 154760	G2V	100.0		89.3	46.8	7.9	3.4	1.2	1.6	91.3		71.6	30.3	1.7	0.6	3.3	1.7
HD 140605	G2V	100.0		89.9	48.2	8.1	3.5	1.3	1.8	91.8		73.2	32.0	1.8	0.7	3.4	1.9
HYAD 15		100.0		90.1	48.5	8.0	3.5	1.3	1.8	92.1		73.7	32.5	1.8	0.7	3.4	1.9
HD 139777A	K0V	100.0		89.8	47.7	8.0	3.4	1.3	1.8	91.7		72.8	31.5	1.7	0.6	3.5	1.9
HD 136274	G8V	100.0		91.4	51.6	8.3	3.5	1.7	2.3	93.4		77.1	36.6	2.0	0.7	3.6	2.4
HYAD 26		100.0		91.6	52.3	8.3	3.6	1.7	2.3	93.5		77.6	37.3	2.1	0.7	3.6	2.4
HD 150205	G5V	100.0		91.7	52.3	8.4	3.6	1.7	2.4	93.5		77.6	37.4	2.1	0.8	3.8	2.4
HYAD 21		100.0		92.8	55.7	8.6	3.7	2.1	2.8	94.6		80.7	41.8	2.4	0.8	3.9	2.9
+02 3001	G8V	100.0		93.0	56.1	8.6	3.6	2.2	3.1	94.8		81.1	42.3	2.4	0.8	4.3	3.2
HD 190571	G8V	100.0	0.3	99.5	95.2	40.0	11.3	3.4	3.6	96.7	0.1	91.4	80.4	16.0	3.0	6.1	3.7
HYAD 183		100.0	0.3	99.6	96.0	41.6	11.7	4.3	4.6	97.5	0.1	93.1	83.8	18.3	3.4	6.7	4.7
HD 140470	K3V	100.0	0.3	99.6	96.2	42.2	11.9	4.5	4.8	97.5	0.1	93.3	84.4	19.0