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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"

18323 results found.

  1. LIGO/Virgo/KAGRA S251105aj: SVOM/VT optical observations and preliminary results on SVOM J2320.0-2901
  2. LIGO/Virgo/KAGRA S251105aj: EP-FXT follow-up observations and preliminary results on SVOM J2320.0-2901
  3. EP251124a: GROWTH-India Telescope optical upper limits
  4. EP251124a: Einstein Probe detection of an X-ray transient
  5. GRB 251116C: Swift-XRT confirmation of fading
  6. GRB 251122A/EP251122A: 1.3m DFOT optical detection
  7. GRB 251122A / EP251122a: Xinglong 2.16m optical observation
  8. EP251118A: 3.6m DOT optical afterglow detection
  9. EP251122a: refined analysis of the EP-WXT and EP-FXT observations
  10. GRB 251122A / EP251122a: WFST optical observations
  11. GRB 251122A/EP251122a: SVOM/VT optical observations with VHF data
  12. GRB 251122A/EP251122a: Additional, deeper LCO optical r band upper limit
  13. GRB 251122A / EP251122a: LCO optical upper limits
  14. EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations
  15. GRB 251122A/EP251122a: SVOM/C-GFT upper limit
  16. GRB 251122A / EP251122a: SVOM detection of a long burst
  17. EP251122a: Einstein Probe detection of an X-ray transient
  18. EP251118a: Continued Optical Detection with Kinder observations
  19. LIGO/Virgo/KAGRA S251105aj: SVOM/ECLAIRs detection of a high-energy transient SVOM J2320.0-2901 through targeted search
  20. GRB 251121A: Swift/BAT-GUANO localization skymap of a short burst
  21. EP251118a: Xinglong-2.16m optical observation
  22. Fermi trigger No 785388351: Global MASTER-Net observations report
  23. EP251118A: 1.3m DFOT optical afterglow detection
  24. GRB 251118A: Swift/UVOT Detection
  25. EP251118a / GRB 251118C: SAO RAS optical observations
  26. GRB 251118A: Swift-XRT afterglow detection
  27. GRB 251103A: SVOM/ECLAIRs and SVOM/GRM joint refined analysis
  28. EP251118a: Optical detection with Kinder observations
  29. LIGO/Virgo/KAGRA S251112cm: SVOM/VT optical observations and preliminary results
  30. EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
  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. GRB 251118A: Swift ToO observations
  40. EP251118a: Einstein Probe detected of a fast X-ray transient
  41. LIGO/Virgo/KAGRA S251112cm: Upper limits from Glowbug gamma-ray observations
  42. GRB 251117A: Swift/BAT-GUANO localization skymap of a short burst
  43. GRB 251117A: SVOM/GRM observation of a short burst
  44. GRB 251117A: Tiled Swift observations
  45. LIGO/Virgo/KAGRA S251117dq: Identification of a GW compact binary merger candidate
  46. LIGO/Virgo/KAGRA S251112cm: WFST follow-up observations and preliminary results
  47. EP251023a: Assy AZT-20 optical observations
  48. EP251023a: UAFO and AbAO optical observations
  49. LIGO/Virgo/KAGRA S251112cm: EP-FXT follow-up observations
  50. The EP-WXT trigger 01709247588: more evidence of flaring star from Mondy optical observations
  51. GRB 251025B: further Mondy optical observations
  52. GRB 251111A: Mondy optical upper limit
  53. LIGO/Virgo/KAGRA S251116en: Identification of a GW compact binary merger candidate
  54. LIGO/Virgo/KAGRA S251112cm: Observations with the NSF-DOE Vera C. Rubin Observatory
  55. GRB 251116B: LCO optical upper limits
  56. GRB 251116C: LCO optical upper limits
  57. GRB 251116B: SVOM detection of a burst
  58. LIGO/Virgo/KAGRA S251112cm: GRANDMA observations of the skymap
  59. GRB 251115A: Tiled Swift observations
  60. GRB 251013C: joint SVOM/ECLAIRs-GRM refined analysis
  61. LIGO/Virgo/KAGRA S251112cm: DECam GW-MMADS candidates
  62. LIGO/Virgo/KAGRA S251112cm: Candidates from the Zwicky Transient Facility
  63. LIGO/Virgo/KAGRA S251112cm: TROVE Vetting of TNS Candidates
  64. LIGO/Virgo/KAGRA S251112cm: FTW observations of galaxies within localization region
  65. GRB 251112A: Swift/UVOT Upper Limits
  66. LIGO/Virgo/KAGRA S251112cm: Coverage and upper limits from MAXI/GSC observations
  67. Swift Trigger 1413695: a possible GRB 251112A
  68. GRB251111A: 1.3m DFOT optical upper limit
  69. LIGO/Virgo/KAGRA S251112cm: Identification of a GW compact binary merger candidate
  70. GRB 251111A: Swift-XRT afterglow detection
  71. GRB 251111A: SVOM/VT optical observations with X-band data
  72. GRB 251111A: SVOM/VT optical observations with VHF data
  73. GRB 251111A: LCO optical observation
  74. GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
  75. GRB 251106A: Swift/UVOT Upper Limits
  76. LIGO/Virgo/KAGRA S251108fi: DDOTI Optical Candidate
  77. LIGO/Virgo/KAGRA S251108fi: Identification of a GW compact binary merger candidate
  78. GRB 251102B: SVOM/GRM observation
  79. LIGO/Virgo/KAGRA S251108dn: Identification of a GW compact binary merger candidate
  80. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) fading of the optical counterpart
  81. GRB 251106A: Swift-XRT afterglow detection
  82. GRB 251106A: Kilonova-Catcher optical upper limit
  83. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) detection of a likely optical counterpart
  84. GRB 251106A: MASTER optical observations
  85. GRB 251106A: SVOM detection of a burst
  86. EP251102a: Xinglong 2.16-m clear-band observations of the optical counterpart
  87. GRB 251105A: Swift/BAT-GUANO localization skymap of a burst
  88. GRB 251104A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  89. GRB 251105B: AstroSat CZTI detection of a short burst with extended emission
  90. GRB 251023A: SVOM/ECLAIRs detection of a burst through targeted search
  91. GRB 251103B: Swift/UVOT Upper Limits
  92. LIGO/Virgo/KAGRA S251105aj: Identification of a GW compact binary merger candidate
  93. GRB 251104A: SVOM detection of a burst
  94. GRB 251103A: WFST optical observations
  95. GRB 251103A: Xinglong 2.16m optical detection
  96. GRB 251103A: KAIT optical observations
  97. GRB 251103B: Nanshan/HMT optical upper limit
  98. GRB 251013C: 7DT detection and Medium-band SED of Afterglow
  99. GRB 251103B: MITSuME Akeno optical upper limits
  100. LIGO/Virgo/KAGRA S251103f: Identification of a GW compact binary merger candidate

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