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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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.

Advanced Search Examples (click to copy):

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

22043 results found.

  1. GRB 251116C: Swift-XRT confirmation of fading
  2. GRB 251122A/EP251122a: FTW optical and NIR observations
  3. GRB 251122A/EP251122A: 1.3m DFOT optical detection
  4. GRB 251122A / EP251122a: Xinglong 2.16m optical observation
  5. EP251118A: 3.6m DOT optical afterglow detection
  6. EP251122a: refined analysis of the EP-WXT and EP-FXT observations
  7. GRB 251122A / EP251122a: WFST optical observations
  8. GRB 251122A/EP251122a: SVOM/VT optical observations with VHF data
  9. GRB 251122A/EP251122a: Additional, deeper LCO optical r band upper limit
  10. GRB 251122A / EP251122a: LCO optical upper limits
  11. EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations
  12. GRB 251122A/EP251122a: SVOM/C-GFT upper limit
  13. GRB 251122A / EP251122a: SVOM detection of a long burst
  14. EP251122a: Einstein Probe detection of an X-ray transient
  15. EP251118a: Continued Optical Detection with Kinder observations
  16. LIGO/Virgo/KAGRA S251105aj: SVOM/ECLAIRs detection of a high-energy transient SVOM J2320.0-2901 through targeted search
  17. LIGO/Virgo/KAGRA S251112cm: SOAR spectroscopy of three TROVE TNS candidates
  18. GRB 251121A: Swift/BAT-GUANO localization skymap of a short burst
  19. GRB 251121A: Glowbug gamma-ray detection of a likely short burst
  20. EP251118a: Xinglong-2.16m optical observation
  21. EP251118A: 1.3m DFOT optical afterglow detection
  22. GRB 251118A: Swift/UVOT Detection
  23. EP251118a / GRB 251118C: SAO RAS optical observations
  24. GRB 251118A: Glowbug gamma-ray detection
  25. GRB 251118A: Swift-XRT afterglow detection
  26. EP251118a: Optical detection with Kinder observations
  27. LIGO/Virgo/KAGRA S251112cm: SVOM/VT optical observations and preliminary results
  28. EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
  29. GRB 251116C: NOT optical observations
  30. GRB 251118C: Glowbug gamma-ray detection of the fast X-ray transient EP251118A
  31. GRB 251118C: Swift/BAT rates detection of a burst with a possible association with EP 251118A
  32. GRB 251117A: Swift-XRT observations
  33. GRB 251118C: SVOM/GRM observation of a possible gamma-ray counterpart of EP251118a
  34. GRB 251119A: SVOM trigger sb25111901 is not a GRB
  35. EP251118a: VLT near-infrared observation
  36. GRB 251116D: SVOM/GRM observation of a long GRB
  37. GRB 251119A: SVOM detection of a possible burst
  38. EP251118a: NOT candidate optical counterpart
  39. EP251118a: Einstein Probe detected of a fast X-ray transient
  40. LIGO/Virgo/KAGRA S251112cm: Upper limits from Glowbug gamma-ray observations
  41. GRB 251117A: FTW Observations of Swift candidate X-ray sources
  42. GRB 251115A: Swift-XRT observations
  43. GRB 251117A: Swift/BAT-GUANO localization skymap of a short burst
  44. GRB 251117A: SVOM/GRM observation of a short burst
  45. LIGO/Virgo/KAGRA S251117dq: Identification of a GW compact binary merger candidate
  46. GRB 251116C: Swift/BAT arcminute localization of a burst
  47. LIGO/Virgo/KAGRA S251112cm: J-GEM follow-up observations
  48. GRB 251116B: SVOM/VT optical upper limit
  49. LIGO/Virgo/KAGRA S251112cm: WFST follow-up observations and preliminary results
  50. GRB 251116C: Swift-XRT observations
  51. GRB 251116D: Glowbug gamma-ray detection
  52. EP251023a: Assy AZT-20 optical observations
  53. EP251023a: UAFO and AbAO optical observations
  54. GRB 251116D: AstroSat CZTI detection
  55. The EP-WXT trigger 01709247588: more evidence of flaring star from Mondy optical observations
  56. GRB 251116C: SVOM/VT optical upper limit
  57. GRB 251025B: further Mondy optical observations
  58. GRB 251111A: Mondy optical upper limit
  59. LIGO/Virgo/KAGRA S251116en: Identification of a GW compact binary merger candidate
  60. LIGO/Virgo/KAGRA S251112cm: Observations with the NSF-DOE Vera C. Rubin Observatory
  61. GRB 251116B: LCO optical upper limits
  62. GRB 251116C: LCO optical upper limits
  63. GRB 251116C: SVOM detection of a burst
  64. IceCube-Cascade 251112A: Upper limits from a search for additional neutrino events in IceCube
  65. LIGO/Virgo/KAGRA S251112cm: GRANDMA observations of the skymap
  66. LIGO/Virgo/KAGRA S251112cm: DECam GW-MMADS candidates
  67. GRB 251113A: Glowbug gamma-ray detection
  68. LIGO/Virgo/KAGRA S251112cm: ATLAS targeted observations of the skymap
  69. LIGO/Virgo/KAGRA S251112cm: Swift XRT observations, 20 X-ray sources
  70. IPN triangulation of GRB 251108C
  71. LIGO/Virgo/KAGRA S251112cm: FTW observations of galaxies within localization region
  72. GRB 251112A: Swift/UVOT Upper Limits
  73. GRB 251108C: AstroSat CZTI detection
  74. LIGO/Virgo/KAGRA S251112cm: Coverage and upper limits from MAXI/GSC observations
  75. GRB 251108B: Glowbug gamma-ray detection
  76. Swift Trigger 1413695: a possible GRB 251112A
  77. LIGO/Virgo/KAGRA S251112cm: Upper limits from Fermi-GBM Observations
  78. LIGO/Virgo/KAGRA S251112cm: NED Galaxies in the 3-Initial Localization Volume
  79. GRB251111A: 1.3m DFOT optical upper limit
  80. LIGO/Virgo/KAGRA S251112cm: Identification of a GW compact binary merger candidate
  81. GRB 251106B: Glowbug gamma-ray detection of a likely short burst
  82. GRB 251111A: Swift-XRT afterglow detection
  83. GRB 251111A: SVOM/VT optical observations with X-band data
  84. GRB 251111A: Swift-XRT observations
  85. GRB 251111A: SVOM/VT optical observations with VHF data
  86. GRB 251111A: KAIT optical upper limit
  87. GRB 251111A: LCO optical observation
  88. GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
  89. GRB 251106A: Swift/UVOT Upper Limits
  90. LIGO/Virgo/KAGRA S251108fi: DDOTI Optical Candidate
  91. GRB 251105A: AstroSat CZTI detection
  92. LIGO/Virgo/KAGRA S251108fi: One counterpart neutrino candidate from IceCube neutrino searches
  93. LIGO/Virgo/KAGRA S251108fi: Identification of a GW compact binary merger candidate
  94. GRB 251102B: SVOM/GRM observation
  95. LIGO/Virgo/KAGRA S251108dn: Identification of a GW compact binary merger candidate
  96. IPN triangulation of GRB 251105B (possible sGRB with EE)
  97. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) fading of the optical counterpart
  98. GRB 251106A: Swift-XRT afterglow detection
  99. GRB 251106A: Kilonova-Catcher optical upper limit
  100. GRB 251106A: Swift/BAT arcminute localization of a burst

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