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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

18488 results found.

  1. GRB 250909A: Fermi GBM Final Real-time Localization
  2. EP250908b: EP-WXT detection of a fast X-ray transient and EP-FXT observation
  3. GRB 250903A: Swift-XRT afterglow detection
  4. SVOM/sb25090605: detection of an X-ray transient from the LMXB 4U 0513-40
  5. EP250905a: Liverpool Telescope i-band upper limits
  6. LIGO/Virgo/KAGRA S250830bp: DECam/SOAR GW-MMADS updates
  7. EP250905b: EP-FXT follow-up observation
  8. EP250905a: Liverpool Telescope observations
  9. EP250905a: refined analysis of the EP-WXT and EP-FXT observations
  10. EP250905b: EP-WXT detection of a fast X-ray transient
  11. EP250905a: JinShan likely optical counterpart detection
  12. GRB 250905A: Swift/UVOT Upper Limits
  13. EP250905a: Einstein Probe detection of an X-ray transient
  14. GRB250904A: Liverpool Telescope upper limits
  15. GRB 250905A: Enhanced Swift-XRT position
  16. GRB 250904A: Swift/UVOT Detection
  17. GRB 250903A: Swift/UVOT detection
  18. GRB 250904A: Swift-XRT refined Analysis
  19. EP detected a brightening of LMXB 1ES 1735-26.9
  20. GRB 250905A: KAIT optical upper limit
  21. GRB 250905A: Swift detection of a burst
  22. GRB 250904A: Enhanced Swift-XRT position
  23. GRB 250904A: TRT optical counterpart detection
  24. GRB 250904A: Swift detection of a burst
  25. LIGO/Virgo/KAGRA S250904cv: Identification of a GW compact binary merger candidate
  26. EP250903a: retraction of the LCO candidate, and discovery of the likely counterpart
  27. EP-WXT trigger 01709201209: Liverpool Telescope upper limits
  28. GRB 250830C: VZLUSAT-2 detection
  29. EP250903a: refined analysis of the EP-WXT and EP-FXT observations
  30. LIGO/Virgo/KAGRA S250904br: Identification of a GW compact binary merger candidate
  31. The EP-WXT trigger 01709201209 is likely a flaring star
  32. GRB 250903A: EP-FXT counterpart detection
  33. GRB 250903A: LCO optical observation
  34. GRB 250903A: LCO optical afterglow detection
  35. GRB 250903A: SVOM/VT optical confirmation with VHF data
  36. EP250901a: Mondy, Assy and SAO RAS optical limits
  37. GRB 250903A: TRT optical counterpart detection
  38. EP250903a: TRT optical observations
  39. EP250903a: Einstein Probe detection of an X-ray transient
  40. EP 250827B: Detection of supernova counterpart by LCO.
  41. GRB 250902B: SVOM/GRM observation
  42. EP250827b: SVOM/VT observation of AT 2025wkm
  43. LIGO/VIRGO/KAGRA S250818k: No evidence for radio variability of AT2025ulz in MeerKAT 3 GHz data
  44. GRB 250831A (SVOM trigger sb25083102): KAIT confirmation of stellar flare
  45. GRB 250901A: Swift/UVOT Upper Limit
  46. GRB 250830B: Swift-XRT afterglow detection
  47. GRB 250831A (SVOM trigger sb25083102): confirmation of a stellar flare by SVOM/VT
  48. GRB 250902A: SVOM/GRM observation
  49. EP250828a: Early near-infrared follow-up with MIRAGE on the MDM 1.3m telescope
  50. EP250901a: refined analysis of the EP-WXT and EP-FXT observations
  51. GRB 250901A: EP-FXT follow-up observation
  52. GRB 250901A: SVOM/VT optical afterglow with VHF data
  53. LIGO/Virgo/KAGRA S250830bp: DECam GW-MMADS candidates
  54. GRB 250901A: LCO optical upper limit
  55. LIGO/Virgo/KAGRA S250901cb: Identification of a GW compact binary merger candidate
  56. EP250831a: NOT optical observations and tentative afterglow candidate
  57. EP250827b: Contemporaneous detection of EP X-ray flare EP250827b and ZTF transient ZTF25abmpngy/AT2025wkm
  58. GRB 250901A: SVOM detection of a burst
  59. EP250901a: Mephisto optical upper limits
  60. GRB 250830C: AstroSat CZTI detection of a long burst
  61. EP250901a: Einstein Probe detection of an X-ray transient
  62. EP250831a: EP-FXT follow-up observation
  63. EP250831a: EP-WXT detection of a fast X-ray transient
  64. GRB 250831A: Swift-XRT counterpart detection
  65. GRB 250831A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  66. GRB 250831A: SVOM/VT upper limit with VHF data
  67. GRB 250831A: SVOM detection of a soft burst
  68. EP250830a/GRB 250830B: Einstein Probe detection of an X-ray transient and Swift/XRT follow-up
  69. LIGO/Virgo/KAGRA S250830bp: Identification of a GW compact binary merger candidate
  70. EP-WXT trigger 01709200994: Liverpool Telescope upper limits
  71. LIGO/Virgo/KAGRA S250830m: Identification of a GW compact binary merger candidate
  72. The EP-WXT trigger 01709200994 is likely a flaring star
  73. LIGO/Virgo/KAGRA S250725j: Observations with the NSF-DOE Vera C. Rubin Observatory
  74. LIGO/Virgo/KAGRA S250818k: MeerKAT detection of an increase in radio flux from AT2025ulz
  75. EP250828a: refined analysis of the EP-WXT and EP-FXT observations
  76. EP250828a: Optical counterpart detection with Kinder observations
  77. EP250828a: Liverpool Telescope upper limits
  78. EP-WXT trigger 01709200800 : KAIT optical observations
  79. EP250828a: KAIT optical upper limit
  80. EP250827a: Swift/UVOT Detection
  81. EP250828a: NOT optical counterpart confirmation
  82. EP250828a: SVOM/VT optical candidate
  83. EP250828a: Seimei/TriCCS optical counterpart detection
  84. EP250828a: Optical upper limit with Kinder observations
  85. EP250828a: Einstein Probe detection of an X-ray transient
  86. EP250827a: Preliminary analysis of the EP-WXT and EP-FXT observations
  87. EP250827a: confirmation of optical rebrightening with LCO
  88. GRB 250826A: SVOM/GRM observation
  89. EP250827A: An optical rebrightening was detected by LCO.
  90. The EP-WXT trigger 01709200800 is likely a flaring star
  91. EP250827a: TRT optical observations
  92. EP250827a: Einstein Probe detection of an X-ray transient
  93. LIGO/Virgo/KAGRA S250827l: Identification of a GW compact binary merger candidate
  94. GRB 250806A: HiPERCAM/GTC limits on a possible supernova
  95. LIGO/Virgo/KAGRA S250818k: SAO RAS BTA z-band observations of AT2025ulz
  96. GRB 250821B: AstroSat CZTI detection
  97. LIGO/Virgo/KAGRA S250818k: MASTER predicovery limits of the AT2025ulz/ZTF25abjmnps KN candidate
  98. LIGO/Virgo/KAGRA S250818k: ENGRAVE observations of SN 2025ulz as a type II supernova
  99. EP250821a: MeerKAT radio counterpart
  100. The EP-WXT trigger 01709200707 is likely a flaring star

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