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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.

Advanced Search Examples (click to copy):

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

32713 results found.

  1. GRB 250108B: Gemini-North Candidate Optical Afterglow Detection
  2. GRB 250103A: 1.6m Mephisto optical observations
  3. GRB 250108A:SVOM/VT optical candidate
  4. LIGO/Virgo/KAGRA S250108eo: Identification of a GW compact binary merger candidate
  5. GRB 250108B: Swift/UVOT Upper Limits
  6. GRB 250108A: Swift ToO observations
  7. GRB 250107A: Fermi GBM Observation
  8. GRB 241228B: Fermi-LAT detection
  9. Fermi GRB 250107B: Global MASTER-Net observations report
  10. GRB 250107A: Swift ToO observations
  11. GRB 250107A: Swift/BAT-GUANO arcminute localization of a burst
  12. GRB 250106A: SVOM/VT 2nd optical deep observation
  13. GRB 250101A: J band upper limit by SYSU 80cm telescope
  14. GRB 250106A: NOT optical observations
  15. LIGO/Virgo/KAGRA S250104v: Updated Sky localization
  16. GRB 250103B: REM optical/NIR upper limits
  17. GRB 250101A: REM optical/NIR counterpart detection
  18. GRB 250106A: Swift-XRT observations
  19. GRB 250106A: SVOM/VT optical candidate
  20. GRB 250106A: Swift ToO observations
  21. GRB 241229A: SVOM/VT optical upperlimit
  22. GRB 250103B: LCO/1m optical afterglow candidate detection
  23. GRB 250103B: VLT/X-shooter spectroscopic redshift z = 1.416
  24. GRB 250103A: Swift-XRT observations
  25. GRB 250101A: 1.3m DFOT optical afterglow detection
  26. GRB 241229A: 1.3m DFOT upper limit
  27. GRB 241228B: 1.3m DFOT Optical observations
  28. GRB 241228A: 1.3m DFOT upper limit
  29. GRB 250103A: NOT spectroscopic redshift
  30. GRB 250103B：SVOM/VT optical counterpart
  31. LIGO/Virgo/KAGRA S250104v: Identification of a GW compact binary merger candidate
  32. GRB 250103A: Montarrenti Observatory optical detection
  33. GRB 250101A: further LCOGT optical afterglow observations
  34. GRB 250103A: Redshift 4.01 from OSIRIS+/GTC
  35. GRB 250103A: NOT optical observations
  36. GRB 250103A: TSHAO optical upper limit
  37. GRB 250103A: Fermi GBM Observation
  38. GRB 250103B: LCOGT Optical Upper Limit
  39. IceCube-250102A: Upper limits from a search for additional neutrino events in IceCube
  40. Swift GRB 250103B: Global MASTER-Net observations report
  41. GRB 250103A: SVOM/VT optical counterpart confirmation
  42. EP250101a: Liverpool Telescope optical upper limit
  43. GRB 250103A: Swift ToO observations
  44. IceCube-250101A: Upper limits from a search for additional neutrino events in IceCube
  45. GRB 250101a: Liverpool Telescope optical follow-up
  46. GRB 250103B: SVOM detection of a long burst
  47. GRB 250103A: Xinglong 2.16m Optical Candidate
  48. Fermi GRB 250102A: Global MASTER-Net observations report
  49. GRB 250101B: SVOM/GRM observation
  50. GRB 250103A: GOTO optical upper limit
  51. GRB 250103A: SVOM/C-GFT optical upper limit
  52. GRB 250101A: NUTTelA-TAO / BSTI Optical Limits
  53. EP241231b: optical upper limit with the Liverpool Telescope
  54. EP250101a: Xinglong optical upper limit
  55. GRB 250101A: Swift-BAT refined analysis
  56. GRB 250101A: further SAO RAS optical observations
  57. GRB 250101A: LCO optical counterpart detection
  58. GRB 250101A NUTTelA-TAO / BSTI Early Measurements
  59. GRB 250101A: GMG spectroscopic redshift at z ~ 2.481
  60. GRB 250101A: Swift/UVOT Detection
  61. GRB 250101A: 1.6m Mephisto multi-band optical followup
  62. GRB 250101A: Montarrenti Observatory optical observations and rebrightening
  63. GRB 250101A: LCOGT optical afterglow detection
  64. GRB 250101A: OASDG optical observations
  65. Fermi GRB 250101B: Global MASTER-Net observations report
  66. GRB 250101A: SAO RAS observations of optical brightening
  67. GRB 250101A: AKO Optical Afterglow Detection
  68. GRB 250101A: SAO RAS optical observations
  69. LIGO/Virgo/KAGRA S250101k: Updated Sky localization and Source Classification
  70. GRB 250101A: Xinglong-2.16m spectroscopic redshift
  71. GRB 250101A: SVOM/C-GFT early optical observations
  72. LIGO/Virgo/KAGRA S250101k: Upper limits from Fermi-GBM Observations
  73. GRB 250101A: MASTER earlier OT observations with SOSS emission features
  74. GRB 250101A: Nanshan/HMT optical observations
  75. GRB 250101A : GIT optical detection
  76. GRB 250101A: GMG Optical Observation
  77. GRB 241217a/EP241217b: ATCA Radio Detection
  78. EP241217a: VLA Radio Detection

  79. LIGO/Virgo/KAGRA S250101k: Identification of a GW compact binary merger candidate
  80. GRB 241229B: Continued CrAO ZTSh observations
  81. LIGO/Virgo/KAGRA S241231bg: Updated Sky localization and EM Bright Classification
  82. LIGO/Virgo/KAGRA S241230ev: Updated Sky localization
  83. LIGO/Virgo/KAGRA S241230bd: Updated Sky localization
  84. GRB 241229A: EP-FXT X-ray afterglow confirmation
  85. GRB 241228B: Multiband optical monitoring with 1.6m Mephisto
  86. GRB 241229B: SVOM/GRM observation
  87. LIGO/Virgo/KAGRA S241231bg: Identification of a GW compact binary merger candidate
  88. EP241217A: J band upper limit by SYSU 80cm telescope
  89. LIGO/Virgo/KAGRA S241230ev: Identification of a GW compact binary merger candidate
  90. GRB 241229B: SAO RAS optical upper limit
  91. GRB 241228B: SAO RAS optical observations
  92. GRB 241229B: CrAO ZTSh possible optical counterpart of SVOM/VT confirmation
  93. GRB 241229A: SAO RAS optical observations
  94. GRB 241229B: SVOM/VT optical candidate
  95. GRB 241229A: Swift-XRT observations
  96. Konus-Wind detection of GRB 241228A
  97. GRB 241229A: EP-FXT afterglow candidates
  98. EP240702a: 7DT Optical upper limits
  99. GRB 240606B: 7DT Optical upper limits
  100. LIGO/Virgo/KAGRA S241230bd: Identification of a GW compact binary merger candidate

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